Polymer Battery Module Packaging Sheet and a Method of Manufacturing the Same

ABSTRACT

A polymer battery module packaging sheet includes, as essential components, a base layer ( 61 ), an aluminum layer ( 62 ), chemical conversion coatings ( 64   a,    64   b ) coating the opposite surfaces of the aluminum layer ( 62 ), and an innermost layer ( 63 ). The chemical conversion coatings ( 64   a,    64   b ) are formed by processing the opposite surfaces of the aluminum layer ( 62 ) by a phosphate treatment method. The base layer ( 61 ) and the innermost layer ( 63 ) are bonded to the chemical conversion coatings ( 64   a,    64   b ) of the aluminum layer ( 62 ) with adhesive layers ( 65   a,    65   b ), respectively.

TECHNICAL FIELD

The present invention relates to a moistureproof, formable packagingsheet for forming a package for packaging a polymer battery module witha solid organic electrolyte (polyelectrolyte), resistant to thedetrimental effects of the polymer battery module, and to a method ofmanufacturing the packaging sheet.

BACKGROUND ART

A polymer battery, which is also called a lithium secondary battery,uses a polyelectrolyte, generates current by the migration of lithiumions and has positive and negative electrodes formed of active polymers.

The lithium secondary battery comprises a lithium battery module havinga positive electrode collector (aluminum or nickel), a positiveelectrode active substance layer (metal oxide, carbon black, a metalsulfide, an electrolytic solution or a polymer for forming a positiveelectrode, such as polyacrylonitrile), an electrolytic layer (acarbonate electrolytic solution of propylene carbonate, ethylenecarbonate, dimethyl carbonate or ethylene methyl carbonate, an inorganicsolid electrolyte of a lithium salt or a gelled electrolyte), a negativeelectrode active layer (lithium, an alloy, carbon, an electrolyticsolution or a polymer, such as polyacrylonitrile) and a negativeelectrode collector (copper, nickel, a stainless steel), and a packagecontaining the lithium battery module therein.

The polymer battery is used as a power supply for personal computers,portable terminal devices (portable telephone sets and PDSs), videocameras, electric vehicles, energy storage batteries, robots, artificialsatellites and the like.

The package of the polymer battery is a cylindrical or parallelepipedicmetal can formed by pressing a metal sheet or a pouch formed byprocessing a laminated sheet consisting of a base layer, an aluminumlayer and a sealant layer.

Such known packages for polymer batteries have the following problems.The meal can has rigid walls and hence the shape of the lithium batterymodule is dependent on that of the metal can. Since the hardware isdesigned so as to conform to the shape of the battery, the dimensions ofthe hardware are dependent on the shape of the battery, which reducesthe degree of freedom of designing the shape of the hardware.

A pouch formed by heat-sealing two laminated sheets to contain a polymerbattery module therein and an embossed package formed in the shape of avessel by subjecting the laminated sheet to an embossing process tocontain a polymer battery therein have been developed. The embossedpackage, as compared with the pouch, is a compact package. Satisfactorymoistureproof property, strength including piecing resistance andinsulating property are essential to polymer battery packages.Satisfactory formability is an additional important property of alaminated sheet for forming the embossed package.

More specifically, a packaging laminated sheet having a nylon layer, anadhesive layer, an aluminum layer, an adhesive layer and a castpolypropylene (PP) resin layer is an example of a polymer battery modulepackaging sheet for forming embossed packages. Even if the packaginglaminated sheet is fabricated by a dry lamination process that makes theadhesive layers bond the adjacent layers with stable, high adhesivestrength, sometimes, the packaging laminated sheet is delaminated andthe nylon layer and the aluminum layer are separated when the packaginglaminated sheet is subjected to an embossing process or when a packageformed from the packaging laminated sheet is subjected to a heat-sealingprocess to heat-seal a peripheral part thereof after putting a polymerbattery module in the package. Sometimes, the packaging laminated sheetis delaminated by hydrogen fluoride produced by the interaction of theelectrolyte of the polymer battery module and moisture and the aluminumlayer and the cast PP layer are separated.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a polymer batterymodule packaging sheet excellent in protective property for protecting apolymer battery module and formability, and a method of manufacturingthe same.

According to the present invention, a polymer battery module packagingsheet for packaging a polymer battery module includes, as essentialcomponents, a base layer, an aluminum layer, a chemical conversioncoating, and an innermost layer, wherein the innermost layer consists ofa single layer.

According to the present invention, a polymer battery module packagingsheet for packaging a polymer battery module includes, as essentialcomponents, a base layer, an aluminum layer, a chemical conversioncoating formed by chemical conversion treatment and an innermost layer,wherein the innermost layer consists of an adhesive resin layer and aninnermost resin layer.

According to the present invention, a polymer battery module packagingsheet manufacturing method comprises the steps of: processing one ofsurfaces of an aluminum layer by chemical conversion treatment;dry-laminating the aluminum layer to a base layer with the other surfacethereof not processed by the chemical conversion treatment bonded to thebase layer; and bonding an innermost layer to the surface processed bythe chemical conversion treatment of the aluminum layer by extruding amolten resin for forming the innermost layer in a molten resin film byan extrusion process while a surface of the molten resin film facing thealuminum layer is processed by ozone treatment.

According to the present invention, a polymer battery module packagingsheet manufacturing method comprises the steps of: processing one ofsurfaces of an aluminum layer by chemical conversion treatment;dry-laminating the aluminum layer to a base layer with the other surfacethereof not processed by the chemical conversion treatment bonded to thebase layer; and laminating a film consisting of an innermost layer andan adhesive resin layer to the surface processed by the chemicalconversion treatment of the aluminum layer by a coextrus ion laminationmethod while a surface of a molten resin film forming the adhesive resinlayer facing the aluminum layer by ozone treatment.

According to the present invention, a polymer battery module packagingsheet manufacturing method comprises the steps of: processing one ofsurfaces of an aluminum layer by chemical conversion treatment;dry-laminating the aluminum layer to a base layer; laminating a film ofan adhesive resin forming an innermost layer to the surface processed bythe chemical conversion treatment of the aluminum layer by extruding theadhesive resin by a sandwich lamination method while a surface of thefilm of the molten adhesive resin by ozone treatment.

According to the present invention, a polymer battery module packagingsheet manufacturing method comprises the step of sequentially laminatingat least a base layer, an aluminum layer, a chemical conversion coatingand an innermost layer, wherein the innermost layer is formed of apolyethylene resin (PE resin).

According to the present invention, a polymer battery module packagingsheet manufacturing method comprises the steps of: processing both thesurfaces of an aluminum layer by chemical conversion treatment;dry-laminating a base layer to one of the surfaces of the aluminumlayer; and laminating an innermost layer to the other surface of thealuminum layer by extruding a molten resin in a molten resin film by anextrusion process while a surface of the molten resin film facing thealuminum layer is processed by ozone treatment.

According to the present invention, a polymer battery module packagingsheet manufacturing method comprises the steps of: processing both thesurfaces of an aluminum layer by chemical conversion treatment;dry-laminating a base layer to one of the surfaces of the aluminumlayer; and laminating a film of a molten adhesive resin film for formingan adhesive resin layer, and an innermost layer formed by a coextrusionlamination method to the other surface of the aluminum layer while asurface of the molten adhesive resin film facing the aluminum layer isprocessed by ozone treatment.

According to the present invention, a polymer battery module packagingsheet manufacturing method comprises the steps of: processing both thesurfaces of an aluminum layer by chemical conversion treatment;dry-laminating a base layer to one of the surfaces of the aluminumlayer; and extruding an adhesive resin on the aluminum layer in a moltenadhesive resin film, sandwich-laminating a film forming an innermostlayer to the other surface of the aluminum layer by the molten adhesiveresin film while a surface of the molten adhesive resin film facing thealuminum layer is processed by ozone treatment.

According to the present invention, a polymer battery module packagingsheet manufacturing method comprises the steps of: processing at leastone of surfaces of an aluminum layer by chemical conversion treatment;dry-laminating a base layer to a surface not processed by the chemicalconversion treatment of the aluminum layer; forming a laminated sheet bylaminating a film consisting of an adhesive resin layer and an innermostlayer and formed by a coextrusion lamination method to the surfaceprocessed by the chemical conversion treatment of the aluminum layer;and heating the laminated sheet so that the adhesive resin layer isheated at a temperature not lower than its softening point.

According to the present invention, a polymer battery module packagingsheet manufacturing method comprises the steps of: processing at leastone of surfaces of an aluminum layer by chemical conversion treatment;dry-laminating a base layer to one of the surfaces of the aluminumlayer; forming a laminated sheet by bonding a polypropylene resin film(hereinafter referred to as “PP resin film”) with an adhesive resinlayer of an acid-modified polypropylene resin (hereinafter referred toas “PPa resin”) to the other surface processed by the chemicalconversion treatment of the aluminum layer by a sandwich laminationprocess; and heating the laminated sheet so that the adhesive resinlayer is heated at a temperature not lower than its softening point.

According to the present invention, a polymer battery module packagingsheet manufacturing method comprises the steps of: processing at leastone of surfaces of an aluminum layer by chemical conversion treatment;dry-laminating a base layer to one of the surfaces of the aluminumlayer; forming a laminated sheet by laminating a film consisting of afilm of an acid-modified polyethylene resin (hereinafter referred to as“PEa resin”) and a film of a polyethylene resin (hereinafter referred toas “PE resin”) to the surface processed by the chemical conversiontreatment of the aluminum layer by a coextrusion lamination method; and

heating the laminated sheet so that the film of the PEa resin is heatedat a temperature not lower than the softening point of the PEa resin.

According to the present invention, a polymer battery module packagingsheet manufacturing method comprises the steps of: processing at leastone of surfaces of an aluminum layer by chemical conversion treatment;dry-laminating a base layer to one of the surfaces of the aluminumlayer; forming a laminated sheet by bonding a film of a PE resin with anadhesive resin layer of a PEa resin to the surface treated by thechemical conversion treatment of the aluminum layer by a sandwichlamination process; and heating the laminated sheet so that the adhesiveresin layer is heated at a temperature not lower than the softeningpoint of the Ape resin.

Acceirding to the present invention, a polymer battery module packagingsheet manufacturing method comprises the steps of: processing at leastone of surfaces of an aluminum layer by chemical conversion treatment;dry-laminating a base layer to one of the surfaces of the aluminumlayer; forming a laminated sheet by laminating a film consisting of anadhesive resin film of an acid-modified polypropylene resin (hereinafterreferred to as “PPa resin”) and a film of an ethylene-rich randompolypropylene resin (hereinafter referred to as “ERRPP resin”) to theother surface of the aluminum layer by a coextrusion lamination method;and heating the laminated sheet at a temperature not lower than thesoftening point of the PPa resin.

According to the present invention, a polymer battery module packagingsheet manufacturing method comprises the steps of: processing at leastone of surfaces of an aluminum layer by chemical conversion treatment;dry-laminating a base layer to one of the surfaces of the aluminumlayer; and forming a laminated sheet by heating the surface processed bythe chemical conversion treatment of the aluminum layer at a temperaturenot lower than the softening point of a PPa resin and laminating a filmconsisting of an adhesive resin film of the PPa resin and a film of anethylene-rich random PP resin (hereinafter referred to as “ERRPP resin”)to the surface processed by the chemical conversion treatment of thealuminum layer by a coextrusion lamination method.

According to the present invention, a polymer battery module packagingsheet manufacturing method comprises the steps of: processing at leastone of surfaces of an aluminum layer by chemical conversion treatment;dry-laminating a base layer to one of the surfaces of the aluminumlayer; forming a laminated sheet by bonding an innermost layer of anERRPP resin with an adhesive resin layer of a PPa resin by a sandwichlamination process; and heating the laminated sheet so that the adhesiveresin layer is heated at a temperature not lower than the softeningpoint of the PPa resin forming the adhesive resin layer.

According to the present invention, a polymer battery module packagingsheet manufacturing method comprises the steps of: processing at leastone of surfaces of an aluminum layer by chemical conversion treatment;dry-laminating a base layer to one of the surfaces of the aluminumlayer; and forming a laminated sheet by heating the surface processed bythe chemical conversion treatment of the aluminum layer at a temperaturenot lower than the softening point of a PPa resin and bonding aninnermost layer of an ERRPP resin with an adhesive resin layer of thePPa resin by a sandwich lamination method.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a polymer battery module packaging sheetin a first embodiment according to the present invention;

FIG. 2 is a view of assistance in explaining a polymer battery employingan embossed package;

FIG. 3 is a view of assistance in explaining a method of forming anembossed package;

FIG. 4 is a view of assistance in explaining a method of attaching tabsto a polymer battery module packaging sheet;

FIG. 5 is a sectional view of assistance in explaining packaginglaminated sheets as polymer battery module packaging sheets in a secondembodiment to an eighth embodiment according to the present invention;

FIG. 6 is a perspective view of assistance in explaining a polymerbattery employing a pouch as a package;

FIG. 7 is a view of assistance in explaining a polymer battery employingan embossed package;

FIG. 8 is a view of assistance in explaining a method of forming anembossed package;

FIG. 9 is a diagrammatic view of assistance in explaining a sandwichlamination method to be applied to manufacturing a polymer batterymodule packaging sheet;

FIG. 10 is a diagrammatic view of assistance in explaining a coextrusionlamination method to be applied to manufacturing a polymer batterymodule packaging sheet;

FIG. 11 is a sectional view of assistance in explaining packaginglaminated sheets as polymer battery module packaging sheets in a ninthembodiment and a tenth embodiment according to the present invention;and

FIG. 12 is a diagrammatic view of assistance in explaining a coextrusionlamination method to be applied to manufacturing a polymer batterymodule packaging sheet.

BEST ODE FOR CARRYING OUT THE INVENTION First Embodiment

A polymer battery module packaging sheet in a first embodiment accordingto the present invention is intended for forming an embossed packagehaving a hollow for containing a polymer battery module. The presentinvention will be described with reference to the accompanying drawings.

FIG. 1 is a sectional view of a polymer battery module packaging sheetin a first embodiment according to the present invention.

FIGS. 2( a) to 2(e) are views of polymer packages of different types,and FIGS. 3( a) to 3(d) are views of assistance in explaining anembossed structure, in which FIG. 3( a) is a perspective view, FIG. 3(c) is a sectional view taken on line X-X in FIG. 3( b), and FIG. 3( d)is an enlarged view of a part indicated at Y in FIG. 3( c).

FIGS. 4( a) to 4(f) are views of assistance in explaining a method ofattaching an adhesive film for bonding tabs to a polymer battery modulepackaging sheet.

As shown in FIGS. 2( a) and 2(d), a polymer battery 1 with an embossedpackage includes a package body 5 a formed by embossing a packaginglaminated sheet 10, i.e., a polymer battery module packaging sheet, andprovided with a hollow part 7 and a flange 9, a polymer battery module 2placed in the hollow part 7 of the package body 5 a, and a cover 5 tformed by cutting the packaging laminated sheet 10 and bonded to theflange 9 of the package body 5 a by heat-sealing.

The polymer battery 1, which is also called a lithium secondary battery,employs a polyelectrolyte, generates current by the agency of themigration of lithium ions and has positive and negative electrodescontaining high polymers as active substances.

The polymer battery module 2 of the lithium secondary battery 1 includesa cell part (energy storage part) 3, and tabs (electrodes) 4. The cellpart 3 includes a positive electrode collector (aluminum or nickel), apositive electrode active substance layer (metal oxide, carbon black, ametal sulfide, an electrolytic solution or a polymer for forming apositive electrode, such as polyacrylonitrile), an electrolytic layer (acarbonate electrolytic solution of propylene carbonate, ethylenecarbonate, dimethyl carbonate or ethylene methyl carbonate, an inorganicsolid electrolyte of a lithium salt or a gelled electrolyte), a negativeelectrode active layer (lithium, an alloy, carbon, an electrolyticsolution or a polymer for a negative electrode, such aspolyacrylonitrile) and a negative electrode collector (copper, nickel, astainless steel).

As shown in FIGS. 2( b) and 2(c), two package bodies 5 a may be joinedtogether instead of covering one package body 5 a with the cover 5 t.The entire flanges of the joined package bodies 5 a may be bondedtogether by heat-sealing as shown in FIG. 2( b) or three parts of theflange of the package body 5 a extending along the three sides of thepackage body 5 a may be bonded to those of the other package body 5 a byheat-sealing as shown in FIG. 2( c).

It is desirable that the side walls 8 of the package body 5 a rise asupright as possible relative to the bottom wall as shown in FIG. 2( e)in order that the polymer battery module 2 can be closely contained inthe package body 5 a. Therefore, the packaging laminated sheet must havesufficient ductility, i.e., formability, suitable for forming.

When the packaging laminated sheet is a structure: nylon layer/adhesivelayer/aluminum layer/adhesive layer/cast polypropylene layer, and theadhesive layers are formed by a dry lamination method, it often occursthat parts of the aluminum layer and the base layer forming the sidewalls are separated by delamination when the packaging laminated sheetis subjected to an embossing process and, sometimes, parts of thepackaging laminated sheet forming peripheral parts of the package aredelaminated when the same peripheral parts are subjected to heat-sealingafter putting the polymer battery module in the package. Sometimes, theinner surface of the aluminum foil is corroded by hydrogen fluorideproduced by the interaction of the electrolyte of the polymer batterymodule and moisture and the packaging laminated sheet is delaminated.

The inventors of the present invention made earnest studies to develop apackaging laminated sheet, i.e., a polymer battery module packagingsheet, that will not be delaminated by embossing and heat-sealing andhas satisfactory properties required of battery module packaging sheetsfor packaging a polymer battery, including chemical resistance to thedetrimental effects of a polymer battery module, found that theforegoing problems can be solved by employing an aluminum foil havingboth the surfaces finished by chemical conversion treatment and havemade the present invention. As shown in FIG. 1, the packaging laminatedsheet 10, i.e., a polymer battery module packaging sheet, according tothe present invention includes, at least, a base layer 61, an adhesivelayer 65 a, an aluminum foil (aluminum layer) 62 having surfaces coatedwith chemical conversion coatings (additional chemically convertedlayers) 64 a and 64 b formed by subjecting the opposite surfaces of thealuminum foil 62 to chemical conversion treatment, an adhesive layer 65b and a heat-sealable resin layer (innermost layer) 63. The packaginglaminated sheet 10 is featured by the chemical conversion coatingsformed by subjecting the aluminum foil 62 to chemical conversiontreatment.

Preferably, the base layer 61 of the polymer battery module packagingsheet of the present invention is a polyester or nylon film. Possiblepolyester resins are PE terephthalate (PET) resins, polybutyleneterephthalate (PET) resins, PE naphthalate (PEN) resins, polybutylenenaphthalate (PEN) resins, interpolyester resins, polycarbonate (PC)resins and the like. Possible nylon resins are nylon 6, nylon 66,copolymers of nylon 6 and nylon 66, nylon 610, polymethaxylileneadipamide (MXD6) and the like.

When the polymer battery is used on a piece of hardware, the base layer61 comes into direct contact with the piece of hardware. Therefore, itis basically desirable to form the base layer 61 of an intrinsicallyinsulating resin. Since a film forming the base layer 61 has pinholesand pinholes will be formed in the film during processing, the thicknessof the base layer 61 must be 6 μm or above, preferably, in the range of12 to 25 μm. The base layer 61 may be a laminated film in view ofproviding the base layer 61 with pinhole resistance and improvedinsulating ability.

A laminated film for the base layer 61 includes at least one resin layerconsisting of two or more layers each having a thickness of 6 m orabove, preferably, in the range of 12 to 25 μm. The following laminatedstructures 1) to 7), not shown, are examples of the laminated base layer61.

1) PET resin layer/Nylon layer2) Nylon layer/PET resin layer

To improve the mechanical aptitude (stability when passed throughprocessing machines and a packaging machine) and surface protectingability (heat resistance and electrolyte resistance) of the packagingsheet and to reduce friction between a die and the base layer whenforming the embossed package body, the base layer 11 may consist ofplural layers and the surface of the base layer 11 may be coated with afluorocarbon resin, an acrylic resin or a silicone resin. The base layer11 may be any one of the following laminated films.

3) Fluorocarbon resin layer/PET resin layer (the fluorocarbon resinlayer may be a fluorocarbon resin film or a film formed by spreading aliquid fluorocarbon resin in a film and drying the same.)4) Silicone resin layer/PET resin layer (the silicone resin layer may bea silicone resin film or a film formed by spreading a liquid siliconeresin in a film and drying the same.)5) Fluorocarbon resin layer/PET resin layer/Nylon layer (thefluorocarbon resin layer may be a fluorocarbon resin film or a filmformed by spreading a liquid fluorocarbon resin in a film and drying thesame.)6) Silicone resin layer/PET resin layer/Nylon layer7) Acrylic resin layer/Nylon layer (the acrylic resin layer may be anacrylic resin film or a film formed by spreading an acrylic resin anddrying the same.)

The base layer 61 is laminated to the aluminum foil 62 by a drylamination method, an extrusion lamination method or any suitablemethod.

The aluminum foil 62, which will be also referred to as a barrier layer62, of the polymer battery module packaging sheet prevents thepenetration of moisture into the polymer battery. To avoid the adverseeffect of pinholes that may be formed in the barrier layer 62, tostabilize the workability (ease of fabricating pouches or embossing) andto provide the barrier layer 62 with pinhole resistance, the barrierlayer 62 has a thickness of 15 μm or above and is formed from a metalfoil, such as an aluminum foil or a nickel foil, or a film coated withan inorganic compound, such as silicon dioxide or alumina, byevaporation. Preferably, the barrier layer 62 is an aluminum foil of athickness in the range of 20 to 80 μm.

The inventors of the present invention made studies to reduce pinholesand to prevent the cracking of an embossed package and found thataluminum having an iron content in the range of 0.3 to 9.0% by weight,preferably, 0.7 to 2.0% by weight is more satisfactory in ductility thanaluminum not containing any iron, an aluminum foil (barrier layer 62) ofsuch aluminum is less subject to the formation of pinholes when thepackaging laminated sheet is bent and is more capable of facilitatingforming the side walls of the embossed package than an aluminum foil ofaluminum not containing any iron. Aluminum foils of aluminum having aniron content less than 0.3% by weight are not satisfactorilypinhole-resistant and do not improve the formability of the packaginglaminated sheet. Aluminum foils of aluminum having an iron contentexceeding 0.9% by weight are unsatisfactory in flexibility and affectadversely to the workability of the packaging laminated sheet in forminga pouch.

The flexibility, stiffness and hardness of an aluminum foil formed bycold rolling are dependent on annealing conditions. The presentinvention prefers rather soft, slightly or completely annealed aluminumfoils to those treated by a hardening process and not annealed.

Annealing conditions that affect the flexibility, stiffness and hardnessof aluminum foils may be properly determined according to the requiredworkability (ease of forming pouches or embossed packages) of thepackaging laminated sheet. For example, to prevent the formation ofcreases or pinholes in making a package by an embossing process, a softaluminum foil properly annealed according to the degree of forming maybe used.

The inventors of the present invention found that the separation of thealuminum foil 62 and the base layer 61 during an embossing process canbe effectively prevented, the dissolution and corrosion of the surfacesof the aluminum foil, particularly, aluminum oxide films coating thealuminum foil, by hydrogen fluoride produced by the interaction of theelectrolyte of the polymer battery and moisture can be effectivelyprevented and the adhesion of the aluminum foil 62 to the innermostlayer 63 can be stabilized by forming the chemical conversion coatings64 a and 64 b, i.e., acid-resistant layers 64 a and 64 b, on the surfaceof the aluminum foil 62 by chemical conversion treatment using aphosphate, a chromate, a fluoride or a triazine thiol compound.

It was found through the examination of various chemical conversiontreatment methods that a phosphate treatment method using trivalentchromium phosphate has remarkable effect.

The aluminum foil 62 having the surfaces coated with the chemicalconversion coatings 64 a and 64 b of the polymer battery modulepackaging sheet is laminated to the innermost layer 63 by a drylamination method.

Parts of the innermost layer 63 of the polymer battery module packagingsheet can be bonded together by heat-sealing. Desirably, the innermostlayer 63 is a film of a material having necessary properties including aheat-resistant property, a moistureproof property and press-formability,such as a cast PP resin film, or a material excellent in low-temperatureresistance and impact resistance and having a melting point not lowerthan 115° C., such as a linear low-density PE resin (hereinafterreferred to as “LLDPE resin”), a medium-density PE resin (hereinafterreferred to as “MDPE resin”) or a high-density PE resin (hereinafterreferred to as HDPE resin”).

The packaging laminated sheet 10, i.e., the polymer battery modulepackaging sheet, may be provided, in addition to the base layer 61, thebarrier layer 62 and the innermost layer 63, an intermediate layersandwiched between the barrier layer 62 and the innermost layer 63. Theintermediate layer is employed to enhance the strength of the packaginglaminated sheet 10 and to improve and stabilize the barrier property ofthe packaging laminated sheet.

The base layer 61, the barrier layer 62 and the innermost layer 63,i.e., a cast PP resin film, are laminated to form the packaginglaminated sheet 10. The aluminum foil 62, i.e., the barrier layer 62, issubjected to chemical conversion treatment before lamination to form thechemical conversion coatings 64 a and 64 b on the surfaces of thealuminum foil 62. The opposite surfaces of the aluminum foil 62 issubjected individually to chemical conversion treatment. Chemicalconversion treatment using chromium phosphate applies a chromiumphosphate solution to a surface of the aluminum foil by a roll coatingmethod or the like and heats the aluminum foil at a surface temperaturein the range of 170 to 200° C. to form the acid-resistant layer 64 a onthe surface of the aluminum foil 62.

The base layer 61 is bonded to the surface provided with theacid-resistant layer 64 a of the aluminum foil 62, and the innermostlayer 63, i.e., a heat-sealable resin layer 63, is laminated to theother surface provided with the acid-resistant layer 64 a of thealuminum foil 62 to provide the packaging laminated sheet 10. Thoselayers may be laminated to the aluminum foil 62 by an extrusionlamination method, a dry lamination method or a hot lamination method. Adry lamination method is most preferable from the viewpoint ofproductivity and providing chemical resistance to the detrimental effectof the battery module to be contained in a package formed from thepackaging laminated sheet 10.

Adhesives suitable for forming the adhesive layers 65 a and 65 b of thepackaging laminated sheet 10 include polyester adhesives, polyethyleneimine adhesives, polyether adhesives, polyether urethane adhesives,polyester urethane adhesives and epoxy adhesives. Polyether urethaneadhesives and polyester urethane adhesives are particularly preferable.

The package body 5 a can be made by subjecting the packaging laminatedsheet 10 to an embossing process using a male mold 21 and a female mold22 as shown in FIG. 3( a). The package body 5 a may be of a one-sidepressed type or a two-side pressed type. The one-side pressed type needsdeeper pressing.

A cast PP resin film is a desirable as the innermost layer 63 of thepackaging laminated sheet 10. The cast PP resin film has propertiessuitable for heat-sealing, protective physical properties, such as amoistureproof property and heat resistance, required of the innermostlayer 63 of the packaging laminated sheet 10 and satisfactoryworkability for lamination and embossing. However, the cast PP resinfilm cannot be bonded to a metal member by heat-sealing. Therefore, whenbonding the tabs 4 of the polymer battery 1 to the packaging laminatedsheets 10, adhesive films 6 that can be bonded to both a metal memberand a cast PP resin film by heat-sealing is interposed between the tabs4 and the innermost layers 63 of the packaging laminated sheets 10 asshown in FIGS. 4( a), 4(b) and 4(c) to ensure that gaps between thetables 4 and the innermost layers 63 are sealed. The adhesive films 6may be wound round predetermined parts of the tabs 4 as shown in FIGS.4( d), 4(e) and 4(f).

EXAMPLES

Examples of the packaging laminated sheet 10 in the first embodimentwill be described hereinafter.

A 25 m thick nylon film, a 40 m thick aluminum foil and a 30 m thickcast PP resin film were used as the base layers 61, the barrier layers62 and the innermost layers 63, respectively, of both packaginglaminated sheets in examples and comparative examples.

The chemical conversion treatment used an aqueous solution of a phenolicresin, a chromium fluoride compound and phosphoric acid as a processingliquid. The processing liquid was applied to the surface of the aluminumfoil by a roll coating method in a film, and the film was baked at 180°C. or above. The weight per unit area of the film was 10 mg/m² (dryweight).

An unsaturated carboxylic acid graft random propylene film of 50 μm inthickness was used for forming the adhesive films 6 to seal gaps aroundthe tabs 4. The adhesive films 6 were wound round parts of the tabs 4,the tabs 4 were sandwiched between the packaging laminated sheets andthe packaging laminated sheets and the tabs 4 were bonded together byheat-sealing.

Example 1-1

Both the surfaces of an aluminum foil 62 were processed by chemicalconversion treatment to form chemical conversion coatings 64 a and 64B.A base layer 61 was bonded to the surface provided with the chemicalconversion coating 64 a of the aluminum foil 62 by a dry laminationmethod, and the innermost layer 63, i.e., a cast PP resin film, wasbonded to the other chemical conversion coating 64 b by a dry laminationmethod to form a packaging laminated sheet in Example 1-1.

Forming and Packaging

A package was formed by embossing the packaging laminated sheet inExample 1-1, a polymer battery module 2 was packaged in the package tocomplete a polymer battery. The polymer battery was tested.

Comparative Example 1-1

A packaging laminated sheet in Comparative example 1-1 was faulted underthe same conditions as those under which the packaging laminated sheetin Example 1-1 was formed, except that an aluminum foil 62 included inthe packaging laminated sheet in Comparative example 1-1 was notprocessed by chemical conversion treatment.

Method of Evaluation

1) Delamination during Forming Process

Samples were inspected for the separation of the base layer 61 and thealuminum foil 62 immediately after forming.

2) Chemical Resistance Test

Samples were inspected for the separation of the aluminum foil 62 andthe innermost resin film 63, i.e., a cast PP resin film, after keepingthe samples in an atmosphere of 60° C. and 90% RH in a thermostat forseven days.

3) Delamination during Heat-Sealing Process

Samples were inspected for the separation of the base layer 61 and thealuminum foil 62 immediately after heat-sealing.

Results

No problem arose in the packaging laminated sheet in Example 1-1 duringforming and heat-sealing, and the base layer 61 and the aluminum foil 62were not separated. Forty-five samples among hundred sample packaginglaminated sheets in Comparative example 1-1 were delaminated byheat-sealing. All the hundred sample packaging laminated sheets inComparative example 1-1 were delaminated by the chemical resistancetest.

The chemical conversion treatment of the opposite surfaces of thealuminum foil prevents the separation of the base layer and the aluminumfoil during an embossing process and heat-sealing. The separation of thealuminum foil and the innermost layer can be prevented because thesurfaces of the aluminum foil are not corroded by hydrogen fluoride thatmay be produced by interaction between the electrolyte of the polymerbattery module and moisture.

Second Embodiment

A polymer battery module packaging sheet in a second embodimentaccording to the present invention is a moistureproof, packaginglaminated sheet resistant to chemicals, capable of being manufactured ata high productivity and resistant to cracking when subjected to aheat-sealing process. The polymer battery module packaging sheet and amethod of manufacturing the same will be described.

FIG. 5( a) is a sectional view of a packaging laminated sheet formed byan extrusion lamination process, FIG. 5( b) is a sectional view of apackaging laminated sheet formed by a sandwich lamination process, FIG.5( c) is a sectional view of a packaging laminated sheet formed by acoextrusion lamination process, FIG. 5( d) is an enlarged view of a partY₂ in FIG. 5( b), FIG. 5( f) is an enlarged view of a part Y₁ in FIG. 5(a) and FIG. 5( f) is an enlarged view of a part Y₃ in FIG. 5( c). FIG. 6is a perspective view of assistance in explaining a heat-sealed pouchfor a polymer battery. FIGS. 7( a) to 7(e) are perspective views ofassistance in explaining an embossed package. FIG. 8( a) is aperspective view of assistance in explaining an embossing process forforming an embossed package, FIG. 8( b) is a perspective view ofembossed package body, FIG. 8( c) is a sectional view taken on line X-Xin FIG. 8( b) and FIG. 8( d) is an enlarged view of a part Yin FIG. 8(c). FIG. 9 is a diagrammatic view of assistance in explaining a sandwichlamination process for manufacturing a polymer battery module packagingsheet. FIG. 10 is a diagrammatic view of assistance in explaining acoextrusion lamination process for manufacturing a polymer batterymodule packaging sheet.

The inventors of the present invention made earnest studies to develop apackaging laminated sheet, i.e., a polymer battery module packagingsheet, that will not be delaminated by embossing and heat-sealing andhas satisfactory chemical resistance to the detrimental effects of apolymer battery module, have found that a packaging laminated sheethaving component layers firmly bonded together can be formed byemploying an aluminum foil having both the surfaces finished by chemicalconversion treatment, bonding a base layer to one of the surfaces of thealuminum foil by a dry lamination process, bonding a n resin film to theother surface of the aluminum foil by an extrusion lamination process, asandwich lamination process or a coextrusion lamination process,processing a surface on the side of the aluminum foil of a heat-sealableresin layer or a bonding layer by ozone treatment and heating thepackaging laminated sheet. According to the present invention, both thebonding layer and the heat-sealable resin layer are PE resins. Thepolymer battery module packaging sheet of the present invention isexcellent in workability, can be manufactured by using comparatively inexpensive materials and has satisfactory properties.

Referring to FIG. 5( a) a packaging laminated sheet 10, i.e., a polymerbattery module packaging sheet, in a second embodiment according to thepresent invention includes at least a base layer 11, a bonding layer 16,an aluminum foil (aluminum layer) 12 having surfaces coated withchemical conversion coatings 15 a and 15 b, and a heat-sealable resinlayer 14. A packaging laminated sheet 10 in the second embodiment mayinclude, as shown in FIG. 5( b), a base layer 11, a bonding layer 16, analuminum foil 12 having surfaces coated with chemical conversioncoatings 15 a and 15 b, an adhesive resin layer 13 of an adhesive resinand a heat-sealable resin layer 14. The heat-sealable resin layer 14 isan innermost layer forming an innermost layer by itself or together withthe adhesive resin layer 13.

A first method of manufacturing the packaging laminated sheet 10 shownin FIG. 5( a) forms the chemical conversion coatings 15 a and 15 b onthe opposite surfaces of the aluminum foil (barrier layer) 12 and formsthe heat-sealable resin layer 14 by directly extruding a molten resinfilm on the chemical conversion coating 15 b formed on the inner surfaceof the aluminum foil 12. A surface of the molten resin film forming theheat-sealable resin layer 14 on the side of the aluminum foil 12 isprocessed by ozone treatment to form an ozonated surface 17. Thepackaging laminated sheet 10 thus formed is heated at a temperature notlower than the softening point of the resin forming the heat-sealableresin layer 14. The heat-sealable resin layer 14 may be formed of aLLDPE resin or a MDPE resin.

A second method of manufacturing the packaging laminated sheet 10 shownin FIG. 5( b) forms the chemical conversion coatings 15 a and 15 b onthe opposite surfaces of the aluminum foil (barrier layer) 12, bonds aheat-sealable film for the heat-sealable resin layer 14 to the chemicalconversion coating 15 b formed on the inner surface of the aluminum foil12 with the adhesive resin layer 13 by a sandwich lamination method. Asurface of a molten adhesive resin film for the adhesive resin layer 13on the side of the aluminum foil 12 is processed by ozone treatment toform the ozonated surface 17. The packaging laminated sheet 10 thusformed is heated at a temperature not lower than the softening point ofthe adhesive resin layer 13. The adhesive resin layer 13 may be formedof a LLDPE resin or a MDPE resin.

A third method of manufacturing the packaging laminated sheet 10 shownin FIG. 5( c) forms chemical conversion coatings 15 a and 15 b on theopposite surfaces of an aluminum foil (barrier layer) 12, bonds aheat-sealable film for a heat-sealable resin layer 14 to the chemicalconversion coating 15 b formed on the inner surface of the aluminum foil12 with an adhesive resin layer 13 by extruding a molten adhesive resinfilm for the adhesive resin layer 13 and a molten resin film for theheat-sealable resin layer 14 by a coextrusion lamination method. Asurface of the molten adhesive resin film for the adhesive resin layer13 on the side of the aluminum foil 12 is processed by ozone treatmentto form the ozonated surface 17. The packaging laminated sheet 10 thusformed is heated at a temperature not lower than the softening point ofthe adhesive resin layer 13. The adhesive resin layer 13 may be formedof a LLDPE resin or a MOPE resin.

The packaging laminated sheet 10 may be heated during a laminationprocess. The first method of manufacturing the packaging laminated sheet10 shown in FIG. 5( a) forms the chemical conversion coatings 15 a and15 b on the opposite surfaces of the aluminum foil 12, heats thechemical conversion coating 15 b at a temperature not lower than thesoftening point of the resin forming the heat-sealable resin layer 14and extrudes the resin for forming the heat-sealable resin layer 14 in afilm on the surface of the heated chemical conversion coating 15 b, andprocesses the surface of the molten resin film for the heat-sealableresin layer 14 on the side of the aluminum foil 12 by ozone treatment.The heat-sealable resin layer 14 may be formed of a LTDPE resin or aMDPE resin.

The second method of manufacturing the packaging laminated sheet 10shown in FIG. 5( b) forms the chemical conversion coatings 15 a and 15 bon the opposite surfaces of the aluminum foil 12, heats the chemicalconversion coating 15 b at a temperature not lower than the softeningpoint of the adhesive resin forming the adhesive resin layer 13 andextrudes the adhesive resin for forming the adhesive resin layer 13 in afilm on the surface of the heated chemical conversion coating 15 b tobond a film for the heat-sealable resin layer 14 to the aluminum foil bysandwich lamination, and processes the surface of the molten adhesiveresin film for adhesive resin layer 13 on the side of the aluminum foil12 by ozone treatment. The adhesive resin layer 13 may be formed of aLLDPE resin or a MDPE resin.

Referring to FIG. 9, when manufacturing the packaging laminated sheet 10shown in FIG. 5( b), a laminated film formed by bonding together thebase layer 11 and the aluminum foil 12 is unwound from a laminated filmroll 37 a, a heat-sealable film is unwound from a heat-sealable filmroll 36, the laminated film and the heat-sealable film are joined andpressed together between a chill roller 34 and a pressure roller 35, anda molten resin film 33 is extruded between the laminated film and theheat-sealable film through a die 32 by an extruder 31 and ozone is blownagainst a surface of the molten resin film 33 on the side of thealuminum foil 12 through an ozone blowing head 51 by an ozonating device50. The packaging laminated sheet 10 thus formed is rolled in apackaging laminated sheet roll 37.

The third method of manufacturing the packaging laminated sheet 10 shownin FIG. 5( c) forms the chemical conversion coatings 15 a and 15 b onthe opposite surfaces of the aluminum foil 12, heats the chemicalconversion coating 15 b at a temperature not lower than the softeningpoint of the adhesive resin forming the adhesive resin layer 13 andextrudes an adhesive resin film for the adhesive resin layer 13 and aheat-sealable resin film for the heat-sealable resin layer 14 on thesurface of the heated chemical conversion coating 15 b by coextrusion tobond the heat-sealable film for the heat-sealable resin layer 14 to thealuminum foil, and processes the surface of the molten adhesive resinfilm for adhesive resin layer 13 on the side of the aluminum foil 12 byozone treatment. The adhesive resin layer 13 may be formed of a LLDPEresin or a MDPE resin.

Referring to FIG. 10, when manufacturing the packaging laminated sheet10 shown in FIG. 5( c), a laminated film formed by bonding together thebase layer 11 and the aluminum foil 12 is unwound from a laminated filmroll 46 a, a molten resin film 43 consisting of an adhesive resin filmfor the adhesive resin layer 13 and a heat-sealable film for theheat-sealable resin layer 14 is extruded through a die 42 by extruders41 a and 41 b onto a surface of the laminated film of the base layer 11and the aluminum foil 12, and ozone is blown against a surface of themolten resin film 43 on the side of the aluminum foil 12 through anozone blowing head 51 by an ozonating device 50. The packaging laminatedsheet 10 thus formed is rolled in a packaging laminated sheet roll 46.

An ozone treatment method employed by the present invention blows ozonegenerated by an ozone generator against the surface of the molten resinfilm. Thus a surface processed by ozone treatment of the resin film onthe side of the aluminum foil 12 is polarized, which improves theadhesive strength between the chemical conversion coating 15 b formed onthe aluminum foil 12, and the heat-sealable resin layer 14 or theadhesive resin layer 13. The extruded resin film can be firmly bonded tothe chemical conversion coating by forming the molten resin film whilethe aluminum foil 12 is heated or by heating the aluminum foil 12 afterforming the molten resin film on the aluminum foil 12.

The present invention employs an ozone generator that generates an ozonegas of an ozone concentration in the range of 0.6 to 10 g/m³ at an ozonegenerating rate in the range of 2 to 20 l/min. An ozone gas of an ozoneconcentration of 400 g/m³ or below is blown against the resin film.

The packaging laminated sheet 10 is heated for postheating at atemperature not lower than the softening point of the resin forming themolten resin film extruded onto the chemical conversion coating.

The packaging laminated sheet 10 is heated for preheating so that thesurface facing the molten resin film of the chemical conversion coatingis heated at a temperature not lower than the softening point of theresin forming the molten resin film.

The package body 5 a for containing the polymer battery module 2, andthe cover 5 t are formed from the packaging laminated sheet, i.e., thepolymer battery module packaging sheet. A pouch as shown in FIG. 6 or anembossed package as shown in FIG. 7( a), 7(b) or 7(c) is used forpackaging the polymer battery module 2. The pouch may be a pillow-typepouch as shown in FIG. 6, a three-sided seal pouch or a four-sided sealpouch.

The embossed package may be such as having a package body 5 a having ahollow part 7 as shown in FIG. 7( a), such as formed by joining togethertwo package bodies 5 a each having a hollow part 7 and a flange andbonding together the corresponding four sides of the flanges as shown inFIG. 7( b) after putting a polymer battery module therein or such asformed by joining together two package bodies 5 a each having a hollowpart 7 and a flange and bonding together the corresponding three sidesof the flanges as shown in FIG. 7( c) after putting a polymer batterymodule 2 therein.

Materials of the component layers of the packaging laminated sheet 10according to the present invention and a method of laminating thecomponent layers will be described hereinafter.

The base layer 11 of the packaging laminated sheet according to thepresent invention is a film of an oriented polyester resin or anoriented nylon resin. Possible polyester resins are PET resins, PBTresins, PEN resins, inteLpolyester resins, PC resins and the like.Possible nylons, i.e., polyamide resins, are nylon 6, nylon 66,copolymers of nylon 6 and nylon 66, nylon 610, polymethaxylileneadipamide (MXD6) and the like.

When the polymer battery is used on a device (hardware), the base layer11 touches the device. Therefore, it is desirable to form the base layer11 of an intrinsically insulating resin. Since a film forming the baselayer 11 has pinholes and pinholes will be formed in the film duringprocessing, the thickness of the base layer 11 must be 6 μm or above.Preferably, the thickness of the base layer 11 is in the range of 12 to25 μm.

The base layer 11 may be a laminated film in view of providing the baselayer 11 with a high pinhole-resistant property and an improvedinsulating ability.

Preferably, the base layer 11 includes at least one resin layerconsisting of two or more layers each having a thickness of 6 μm orabove, preferably, in the range of 12 to 25 μm. The following laminatedstructures 1) to 7) are examples of the laminated base layer 11.

1) Oriented PET resin layer/Oriented nylon layer

2) Oriented nylon layer/Oriented PET layer

To improve the mechanical aptitude (stability when passed throughprocessing machines and a packaging machine) and surface protectingability (heat resistance and electrolyte resistance) of the packagingsheet and to reduce friction between a die and the base layer 11 whenforming the embossed package body, it is preferable that the base layer11 consists of plural layers and the surface of the base layer 11 iscoated with a coating of a fluorocarbon resin, an acrylic resin, asilicone resin or a polyester resin. The base layer 11 may be any one ofthe following laminated films.

3) Fluorocarbon resin layer/Oriented PET resin layer (the fluorocarbonresin layer may be a fluorocarbon resin film or a film formed byspreading a liquid fluorocarbon resin in a film and drying the same.)

4) Silicone resin layer/Oriented PET resin layer (the silicone resinlayer may be a silicone resin film or a film formed by spreading aliquid silicone resin in a film and drying the same.)

5) Fluorocarbon resin layer/Oriented PET resin layer/Oriented nylonlayer

6) Silicone resin layer/Oriented PET resin layer/Oriented nylon layer

7) Acrylic resin layer/Oriented nylon layer (the acrylic resin layer maybe an acrylic resin film or a film formed by spreading an acrylic resinand drying the same.)

The barrier layer (aluminum layer) 12 prevents the penetration ofmoisture into the polymer battery. To avoid the adverse effect ofpinholes that may be formed in the barrier layer 12, to stabilize theworkability (ease of fabricating pouches or embossing) and to providethe barrier layer 12 with pinhole resistance, the barrier layer 12 has athickness of 15 μm or above and is formed from a foil of a metal, suchas aluminum or nickel, or a film coated with an inorganic compound, suchas silicon dioxide or alumina, by evaporation. Preferably, the barrierlayer 12 is an aluminum foil of a thickness in the range of 20 to 80 μm.

The inventors of the present invention made studies to reduce pinholesand to prevent the cracking of an embossed battery package and foundthat an aluminum having an iron content in the range of 0.3 to 9.0% byweight, preferably, in the range of 0.7 to 2.0% by weight is moresatisfactory in ductility than aluminum not containing any iron, and analuminum foil of such aluminum is less subject to the formation ofpinholes when a laminated sheet including the aluminum foil of suchaluminum is folded and is more capable of facilitating forming walls ofan embossed battery package than an aluminum foil of aluminum notcontaining any iron. Aluminum having an iron content less than 0.3% byweight is unable to form a satisfactorily pinhole-resistant foil anddoes not have improved formability. Aluminum having an iron contentexceeding 9.0% by weight is unsatisfactory in flexibility and affectsadversely to the workability of the laminated sheet in forming a pouch.

The flexibility, stiffness and hardness of an aluminum foil formed bycold rolling are dependent on annealing conditions. The presentinvention prefers rather soft, slightly or completely annealed aluminumfoils to those treated by a hardening process and not annealed.

Annealing conditions that affect the flexibility, stiffness and hardnessof aluminum foils may be properly determined according to the requiredworkability (ease of forming pouches or embossed packages) of thepackaging laminated sheet. For example, to prevent the formation ofcreases or pinholes in making a package by an embossing process, a softaluminum foil properly annealed according to the degree of embossing maybe used.

The inventors of the present invention found through studies that asatisfactory packaging laminated sheet can be formed by using analuminum foil having opposite surfaces coated with the chemicalconversion coatings 15 a and 15 b formed by chemical conversiontreatment as the barrier layer 12. The chemical conversion treatmentforms an acid-resistant film of a phosphate, a chromate, a fluoride or atriazine thiol compound. Thus the separation of the aluminum foil 12 andthe base layer 11 during an embossing process can be prevented, thedissolution and corrosion of the surfaces of the aluminum foil 12,particularly, aluminum oxide films coating the aluminum foil, byhydrogen fluoride produced by the interaction of the electrolyte of thepolymer battery module and moisture can be effectively prevented, theadhesive property (wettability) of the surface of the aluminum foil 12is improved, the separation of the base layer and the aluminum foil canbe prevented and the separation of the aluminum foil and the innermostlayer due to the effect of hydrogen fluoride produced by the interactionbetween the electrolyte and moisture can be effectively prevented by thechemical conversion treatment of the aluminum foil.

It was found through experimental chemical conversion treatment usingvarious substances that chemical conversion treatment method using amixture of a phenolic resin, trivalent chromium phosphate and phosphoricacid has satisfactory effect.

When the packaging laminated sheet is intended for use for formingpouches, only one surface on the side of the innermost layer of thealuminum foil needs to be processed by the chemical conversiontreatment.

When both the surfaces of the aluminum foil are coated with the chemicalconversion coatings 15 a and 15 b, the separation of the aluminum foiland the base layer can be prevented when processing the packaginglaminated sheet to form an embossed package. The packaging laminatedsheet including the aluminum foil having both the surfaces coated withthe chemical conversion coatings may be used for forming pouches.

As mentioned above, when the polymer battery module packaging sheetmanufacturing method is used, the heat-sealable resin layer 14 or theadhesive resin layer 13 for bonding the heat-sealable resin layer 14 tothe aluminum foil 12 may be a film of a PE resin.

When a film of a PE resin or a PEa resin for forming the adhesive resinlayer 13 is bonded to the chemical conversion coating 15 b by a sandwichlamination process, the adhesion of the film of the PE resin or the PEaresin to the chemical conversion coating 15 b is insufficient. If anemulsion of the PEa resin is applied to the chemical conversion coating15 b by a roll coating method, the emulsion is dried in an emulsionfilm, the emulsion film is baked at a temperature in the range of 170 to200° C. and the adhesive resin layer 13 of the PEa resin is bonded tothe chemical conversion coating 15 b by a sandwich lamination process,the adhesive strength between the chemical conversion coating 15 b andthe adhesive resin layer 13 is improved. However, the emulsion film isbaked at a very low baking speed and the efficiency of the adhesiveresin layer forming process is very low.

The inventors of the present invention made studies to develop a bondingmethod capable of bonding the adhesive resin layer 13 and the chemicalconversion coating 15 b with stable adhesive strength and have foundthat a packaging laminated sheet 10 having component layers bondedtogether with desired adhesive strength can be formed by bonding a baselayer 11 to one of the surfaces processed by chemical conversiontreatment of a barrier layer 12 by a dry lamination process while themolten resin film is subjected to ozone treatment and heating thepackaging laminated sheet 10 or by subjecting the molten resin film toozone treatment, heating the aluminum foil.

The packaging laminated sheet 10 may be heated by any one of a contactheating method using a hot roller, a hot air heating method using hotair and an infrared heating method using near or far infrared rays,provided that the adhesive resin can be heated at a temperature notlower than the softening point thereof.

PPa resins and PEa resins are possible resins for forming theheat-sealable resin layer 14. The packaging laminated sheetmanufacturing method according to the present invention may use PEresins excellent in protective performance, workability andheat-scalability. Possible PE resins are MDPE resins, low-density PEresins (hereinafter referred to as “LDPE resins”), LLDPE resins andhigh-density PE resins (hereinafter referred to as “HDPE resins”).Preferably, the first method forms the heat-sealable resin layer of aLLDPE resin or a MDPE resin. The second and the third method may use aMDPE resin or a LLDPE resin as the adhesive resin, and may use a LLDPEresin or a MDPE resin for forming the heat-sealable resin layer 14 mayuse a film of a LLDPE resin or a MMDPE resin as the heat-sealable resinlayer 14.

Desired Physical Properties of the LLDPE Resin are:

Softening point: 70° C. or above

Melting point: 112° C. or above

Density: 0.91 or above

Desired Physical Properties of the MDPE Resin are:

Softening point: 80° C. or above

Melting point: 120° C. or above

Density: 0.92 or above

The following are resins or combinations of resins for forming theheat-sealable resin layer 14, or the adhesive resin layer 13 and theheat-sealable resin layer 14.

Single-Film Extrusion

Heat-sealable resin layer 14: MDPE resin

Adhesive Resin Layer 13 as Heat-Sealable Resin Layer

(1) Adhesive resin layer 13 of MDPE resin/Heat-sealable resin layer 14of LLDPE resin

(2) Adhesive resin layer 13 of MDPE resin/Heat-sealable resin layer 14of MOPE resin

The LLDPE and the MDPE resins may contain, as additives, alow-crystalline ethylene-butene copolymer, a low-crystallinepropylene-butene copolymer, a terpolymer of ethylene, butene andpropylene, silica, zeolite, an antiblocking agent (AB agent), such asacrylic resin beads, and/or a fatty amide lubricant.

The packaging laminated sheet 10 may have, in addition to the base layer11, the barrier layer 12, the adhesive resin layer 13 and theheat-sealable resin layer 14 of a PE resin, an intermediate layer of abiaxially oriented film of a polyimide resin or a PET resin sandwichedbetween the barrier layer 12 and the heat-sealable resin layer 14. Theintermediate layer is used to enhance the strength of the packaginglaminated sheet to improve and stabilize barrier property and to preventshort circuit due to contact between the tabs and the barrier layerduring a heat-sealing process.

The component layers of the packaging laminated sheet 10 may beprocessed by a surface activating treatment, such as a corona dischargetreatment, a blasting treatment, an oxidation treatment or ozonetreatment, to improve and stabilize film forming property, laminationproperty, formability (ease of forming pouches or embossed packages).The packaging laminated sheet may be coated with liquid paraffin in acoating weight in the range of 2 to 6 g/m².

Desirably, the base layer 11 of the packaging laminated sheet 10 islaminated to the chemical conversion coating of the barrier layer 12 bya dry lamination method.

Possible adhesive resins for forming the bonding layer 16 bonding thebase layer 11 to the chemical conversion coating 15 a of the barrierlayer 12 are polyester resins, polyethylene imine resins, polyetherresins, cyanoacrylate resins, urethane resins, organic titaniumcompounds, polyether-ure-thane resins, epoxy reins, polyester-urethaneresins, imide resins, isocyanate resins, polyolefin resins and siliconeresins.

Examples

Examples of the polymer battery module packaging sheet in the secondembodiment will be described.

The chemical conversion treatment used an aqueous solution of a phenolicresin, a trivalent chromium fluoride compound and phosphoric acid as aprocessing liquid. The processing liquid was applied to the surface ofthe aluminum foil by a roll coating method in a film, and the film wasbaked at 180° C. or above. The weight per unit area of the film was 10mg/m² (dry weight).

The following examples and comparative examples used an MDPE resinhaving a softening point of 110° C. and a melting point of 125° C., andan LLDPE resin having a softening point of 98° C. and a melting point of115° C.

The ozone treatment process used a slit nozzle to blow ozone against theentire width of an extruded molten resin film. The ozone treatment wascarried out under ozonizing conditions (A) and (B).

Ozonizing Condition (A)

Ozone gas generating rate: 20 l/min

Ozone concentration (as generated): 10 g/m³

Ozone concentration (as used): 400 g/m³

Ozonizing Condition (B)

Ozone gas generating rate: 2 l/min

Ozone concentration (as generated): 0.6 g/m³

Ozone concentration (as used): 5 g/m³

Packaging laminated sheets in Examples 2-1 to 2-3 and Comparativeexamples 2-1 to 2-3 and 2-7 to 2-9 were subjected to heat-sealing toform 50 mm×80 mm pillow type pouches and polymer battery modules 2 weresealed in the pillow type pouches, respectively.

Packaging laminated sheets in Examples 2-4 to 2-6, Comparative examples2-4 to 2-6 and 2-10 to 2-11 were subjected to an embossing process toform embossed packages each having a hollow part of 30 mm×50 mm×3.5 mm.The formability of the packaging laminated sheets was evaluated.

Example 2-1 Pouch

One of the surfaces of a 20 μm thick aluminum foil was subjected tochemical conversion treatment. A 16 μm thick oriented polyester film waslaminated to the other surface, i.e., the surface not processed by thechemical conversion treatment, of the aluminum foil by a dry laminationmethod. A 30 μm thick molten resin film of an MDPE resin for forming aheat-sealable resin layer was extruded onto the surface processed by thechemical conversion treatment of the aluminum foil while a surfacethereof to be joined to the aluminum foil was processed by ozonetreatment to form a heat-sealable resin layer. A packaging laminatedsheet thus formed was heated for postheating at a temperature not lowerthan the softening point of the MDPE resin to obtain a packaginglaminated sheet in Example 2-1.

Example 2-2 Pouch

Both the surfaces of a 20 μm thick aluminum foil were subjected tochemical conversion treatment. A 12 μm thick oriented polyester film waslaminated to one of the surfaces of the aluminum foil by a drylamination method. A 30 μm thick molten resin film of an MDPE resin forforming a bonding layer was extruded onto the other surface processed bythe chemical conversion treatment of the aluminum foil while a surfacethereof to be joined to the aluminum foil was processed by ozonetreatment to form an adhesive resin layer, and a 40 μm thick LLDPE resinfilm was bonded to the aluminum foil by the adhesive resin layer by asandwich lamination method. A packaging laminated sheet thus formed washeated for postheating at a temperature not lower than the softeningpoint of the MDPE resin to obtain a packaging laminated sheet in Example2-2.

Example 2-3 Pouch

One of the surfaces of a 20 μm thick aluminum foil was subjected tochemical conversion treatment. A 16 μm thick oriented polyester film waslaminated to the other surface not processed by the chemical conversiontreatment of the aluminum foil by a dry lamination method. A 20 μm thickfilm of a molten MDPE resin for forming an adhesive resin layer and a 30μm thick film of a molten LLDPE resin for forming a heat-sealable resinlayer were coextruded through a coextrusion die onto the surfaceprocessed by the chemical conversion treatment of the aluminum foilwhile a surface to be joined to the aluminum foil of the molten resinfilm of the MDPE resin was processed by ozone treatment. A packaginglaminated sheet thus formed was heated for postheating at a temperaturenot lower than the softening point of the MDPE resin to obtain apackaging laminated sheet in Example 2-3.

Example 2-4 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick oriented nylon film waslaminated to one of the surfaces of the aluminum foil by a drylamination method. A 30 μm thick molten resin film of an MOPE resin forforming a heat-sealable resin layer was extruded onto the other surfaceof the aluminum foil while a surface thereof to be joined to thealuminum foil was processed by ozone treatment. A packaging laminatedsheet thus formed was heated for postheating at a temperature not lowerthan the softening point of the MOPE resin to obtain a packaginglaminated sheet in Example 2-4.

Example 2-5 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick oriented nylon film waslaminated to one of the surfaces of the aluminum foil by a drylamination method. A 20 μm thick molten resin film of an MOPE resin forforming an adhesive resin layer was extruded onto the other surface ofthe aluminum foil while a surface thereof to be joined to the aluminumfoil was processed by ozone treatment to form an adhesive resin layer,and a 30 μm thick film of LLDPE resin for forming a heat-sealable resinlayer was bonded to the aluminum foil by the adhesive resin layer by asandwich lamination method. A packaging laminated sheet thus formed washeated for postheating at a temperature not lower than the softeningpoint of the MDPE resin to obtain a packaging laminated sheet in Example2-5.

Example 2-6 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A laminated film as a base layerconsisting of a 12 μm thick biaxially oriented polyester film and a 15μm thick biaxially oriented nylon film was laminated to one of thesurfaces of the aluminum foil by a dry lamination method with the nylonfilm in contact with the aluminum foil. A 20 μm thick molten resin filmof an MDPE resin for forming an adhesive resin layer and a 30 μm thickmolten resin film of an LLDPE for forming a heat-sealable resin layerwere coextruded through a coextrusion die while a surface to be joinedto the aluminum foil of the molten resin film of the MDPE resin wasprocessed by ozone treatment. A packaging laminated sheet thus formedwas heated for postheating at a temperature not lower than the softeningpoint of the MDPE resin to obtain a packaging laminated sheet in Example2-6.

Comparative Example 2-1 Pouch

One of the surfaces of a 20 μm thick aluminum foil was subjected tochemical conversion treatment. A 16 μm thick oriented polyester film waslaminated to the other surface not processed by the chemical conversiontreatment of the aluminum foil by a dry lamination method. A 30 μm thickmolten resin film of an MDPE resin for forming a heat-sealable resinlayer was extruded onto the surface processed by the chemical conversiontreatment of the aluminum foil to form a heat-sealable resin layer. Apackaging laminated sheet thus formed was heated for postheating at atemperature not lower than the softening point of the MDPE resin toobtain a packaging laminated sheet in Comparative example 2-1.

Comparative Example 2-2 Pouch

Both the surfaces of a 20 μm thick aluminum foil were subjected tochemical conversion treatment. A 12 μm thick oriented polyester film waslaminated to one of the surfaces of the aluminum foil by a drylamination method. A 30 μm thick molten resin film of an MDPE resin forforming an adhesive resin layer was extruded onto the other surface ofthe aluminum foil to form an adhesive resin layer, and a 40 μm thickfilm of LLDPE resin was bonded to the aluminum foil by the adhesiveresin layer by a sandwich lamination method. A packaging laminated sheetthus formed was heated for postheating at a temperature not lower thanthe softening point of the MDPE resin to obtain a packaging laminatedsheet in Comparative example 2-2.

Comparative Example 2-3 Pouch

One of the surfaces of a 20 μm thick aluminum foil was subjected tochemical conversion treatment. A 16 μm thick oriented polyester film waslaminated to the other surface not processed by the chemical conversiontreatment of the aluminum foil by a dry lamination method. A 20 μm thickmolten resin film of an MDPE resin for forming an adhesive resin layerand a 30 μm thick molten resin film of an LLDPE resin for forming aheat-sealable resin layer were coextruded through a coextrusion die ontothe surface processed by the chemical conversion treatment of thealuminum foil. A packaging laminated sheet thus formed was heated forpostheating at a temperature not lower than the softening point of theMDPE resin to obtain a packaging laminated sheet in Comparative example2-3.

Comparative Example 2-4 Embossed Package

One of the surfaces of a 40 μm thick aluminum foil was subjected tochemical conversion treatment. A 256 μm thick oriented nylon film waslaminated to the other surface not processed by the chemical conversiontreatment of the aluminum foil by a dry lamination method. A 30 μm thickmolten resin film of an MDPE resin for forming a heat-sealable resinlayer was extruded onto the surface processed by the chemical conversiontreatment of the aluminum foil. A packaging laminated sheet thus formedwas heated for postheating at a temperature not lower than the softeningpoint of the MDPE resin to obtain a packaging laminated sheet inComparative example 2-4.

Comparative Example 2-5 Embossed Package

One of the surfaces of a 40 μm thick aluminum foil was subjected tochemical conversion treatment. A 25 μm thick oriented nylon film waslaminated to the other surface not processed by the chemical conversiontreatment of the aluminum foil by a dry lamination method. A 20 μm thickmolten resin film of an MOPE resin for forming an adhesive resin layerwas extruded onto the surface processed by the chemical conversiontreatment of the aluminum foil and a 30 μm thick film of an LLDPE resinfor forming a heat-sealable resin layer was bonded to the aluminum foilby a sandwich lamination method. A packaging laminated sheet thus formedwas heated for postheating at a temperature not lower than the softeningpoint of the MDPE resin to obtain a packaging laminated sheet inComparative example 2-5.

Comparative Example 2-6 Embossed Package

One of the surfaces of a 40 μm thick aluminum foil was subjected tochemical conversion treatment. A 25 μm thick oriented nylon film waslaminated to the other surface not processed by the chemical conversiontreatment of the aluminum foil by a dry lamination method. A 20 μm thickmolten resin film of an MDPE resin for forming an adhesive resin layerand a 30 μm thick molten resin film of an LLDPE resin for forming aheat-sealable resin layer were coextruded through a coextrusion die ontothe surface processed by the chemical conversion treatment of thealuminum foil. A packaging laminated sheet thus formed was heated forpostheating at a temperature not lower than the softening point of theMDPE resin to obtain a packaging laminated sheet in Comparative example2-6.

Comparative Example 2-7 Pouch

A packaging laminated sheet in Comparative example 2-7 was formed by thesame method as that by which the packaging laminated sheet in Example2-1 was formed, except that the former was not heated for postheating.

Comparative Example 2-8 Pouch

A packaging laminated sheet in Comparative example 2-8 was formed by thesame method as that by which the packaging laminated sheet in Example2-2 was formed, except that the former was not heated for postheating.

Comparative Example 2-9 Pouch

A packaging laminated sheet in Comparative example 2-9 was formed by thesame method as that by which the packaging laminated sheet in Example2-3 was formed, except that the former was not heated for postheating.

Comparative Example 2-10 Pouch

A packaging laminated sheet in Comparative example 2-10 was formed bythe same method as that by which the packaging laminated sheet inExample 2-4 was formed, except that the former was not heated forpostheating.

Comparative Example 2-11 Pouch

A packaging laminated sheet in Comparative example 2-11 was formed bythe same method as that by which the packaging laminated sheet inExample 2-5 was formed, except that the former was not heated forpostheating.

Comparative Example 2-12 Pouch

A packaging laminated sheet in Comparative example 2-12 was formed bythe same method as that by which the packaging laminated sheet inExample 2-6 was formed, except that the former was not heated forpostheating.

Fabrication of Pouches and Embossed Packages and Packaging

Pouches were formed by processing the packaging laminated sheets inExamples 2-1 to 2-3 and those in Comparative examples 2-1 to 2-3 and 2-7to 2-12. Embossed packages were formed by embossing the packaginglaminated sheets in Examples 2-4 to 2-6 and those in Comparativeexamples 2-4 to 2-6. Polymer battery modules were sealed in thosepouches and embossed packages to form polymer batteries, respectively.The polymer batteries were subjected to tests and their performance wasevaluated. One hundred test samples were tested for each of theaforesaid conditions.

Method of Evaluation

1) Chemical Resistance Test

Samples were inspected for the separation of the aluminum foil and thePE resin film after keeping the samples in an atmosphere of 60° C. and90% RH in a thermostat for seven days.

2) Delamination during Heat-Sealing Process

Samples were inspected for the separation of the base layer and thealuminum foil after keeping the same at 90° C. for 24 hr after thepackaging laminated sheets had been processed for heat-sealing orembossing at 190° C. and 98 N/cm² for 5 s.

Results

None of the packaging laminated sheets in Examples 2-1 to 2-6 formedunder the ozonizing conditions (A) and (B) was delaminated by embossingor heat-sealing and the base layer and the aluminum foil of each of thesample packaging laminated sheets in Examples 2-1 to 2-6 were notseparated by the detrimental effect of the polymer battery modules onthe pouches and embossed packages.

None of the packaging laminated sheets in Comparative examples 2-1 to2-3 was not delaminated during the fabrication of the pouches. However,all the packaging laminated sheets in Comparative examples 2-1 to 2-3were delaminated by the chemical resistance test.

Eighty sample packaging laminated sheets among the hundred samplepackaging laminated sheets in Comparative examples 2-4 to 2-6 weredelaminated by heat-sealing. However, all the packaging laminated sheetsin Comparative examples 2-4 to 2-6 were delaminated by the chemicalresistance test.

None of the packaging laminated sheets in Comparative examples 2-7 to2-9 formed under the ozonizing conditions (A) and (B) was delaminatedheat-sealing for the formation of the pouches. However, all thepackaging laminated sheets in Comparative examples 2-7 to 2-9 weredelaminated by the chemical resistance test.

The base layer and the aluminum foil of each of the sample packaginglaminated sheets in Comparative examples 2-10 to 2-12 formed under theozonizing conditions (A) and (B) were not separated during heat-sealing.However, all the packaging laminated sheets in Comparative examples 2-10to 2-12 were delaminated by the chemical resistance test.

The chemical conversion treatment of the opposite surfaces of thealuminum foil prevents the separation of the base layer and the aluminumfoil during embossing and heat-sealing. The separation of the aluminumfoil and the innermost layer can be prevented because the surfaces ofthe aluminum foil are not corroded by hydrogen fluoride that may beproduced by interaction between the electrolyte of the polymer batterymodule and moisture.

When forming the heat-sealable resin layer of the packaging laminatedsheet by an extrusion lamination method, a sandwich lamination method ora coextrusion lamination method, the surface of the molten resin film ofthe resin to be bonded to the surface processed by the chemicalconversion treatment of the aluminum foil is subjected to the ozonizingtreatment and the packaging laminated sheet as formed is heated at atemperature not lower than the softening point of the resin. Thereforethe heat-sealable resin layer can be formed of a polyethylene resin,which is advantageous in respect of workability and economy as comparedwith acid-modified polyolefin resins and metal crosslinked polyethyleneresins.

Third Embodiment

A packaging laminated sheet, i.e., a polymer battery module packagingsheet, in a third embodiment according to the present invention hascomponent layers laminated with stable adhesive strength and is capableof being efficiently produced. Materials of the packaging laminatedsheet and methods of forming the packaging laminated sheet will bedescribed hereinafter.

The inventors of the present invention found through earnest studies ofpackaging sheets for packaging polymer batteries to develop packaginglaminated sheets that will not be delaminated by heat-sealing that asatisfactory packaging structure can be made by processing the oppositesurfaces of an aluminum foil to chemical conversion treatment,laminating a molten resin film of a PPa resin, such as an unsaturatedcarboxylic acid graft random propylene resin, and a molten resin film ofa PP resin to one of the surfaces of the aluminum foil by a coextrusionlamination method and subjecting the packaging laminated sheet topostheating and have made the present invention.

As shown in FIGS. 5( b) and 5(c), a packaging laminated sheet 10, i.e.,a polymer battery module packaging sheet, in the third embodimentincludes, at least a base layer 11, a bonding layer 16, an aluminum foil12, a chemical conversion coating 15 b formed on one of the oppositesurfaces of the aluminum foil 12, a chemical conversion coating 15 bformed on the other surface of the aluminum foil, an adhesive resinlayer 13 and an innermost layer 14. The adhesive resin layer 13 and theinnermost layer 14 are formed by a coextrusion lamination method.

As shown in FIGS. 5( b) and 5(c), the opposite surfaces of the aluminumfoil (barrier layer) 12 are coated with the chemical conversion coatings15 a and 15 b, the adhesive resin layer 13 and the innermost layer 14are laminated to the inner surface of the aluminum foil 12 by acoextrusion lamination method and a structure thus formed is subjectedto postheating that heats the structure at a temperature not lower thanthe softening point of the adhesive resin forming the adhesive resinlayer 13 to complete the packaging laminated sheet 10.

The base layer 11 is an oriented polyester or nylon film. Possiblepolyester resins are PET resins, PBT resins, PEN resins, PEN resins,interpolyester resins, PC resins and the like. Possible nylon resins arenylon 6, nylon 66, copolymers of nylon 6 and nylon 66, nylon 610,polymethaxylilene adipamide (NXD6) and the like.

When the polymer battery is used on a piece of hardware, the base layer11 comes into direct contact with the piece of hardware. Therefore, itis basically desirable to form the base layer 11 of an intrinsicallyinsulating resin. Since a film forming the base layer 11 has pinholesand pinholes will be formed in the film during processing, the thicknessof the base layer 11 must be 6 μm or above, preferably, in the range of12 to 25 μm.

The base layer 11 may be a laminated film in view of providing the baselayer 11 with pinhole resistance and improved insulating ability.

A laminated film for the base layer 11 includes at least one resin layerconsisting of two or more layers each having a thickness of 6 μm orabove, preferably, in the range of 12 to 25 μm. The following laminatedstructures 1) to 7), not shown, are examples of the laminated base layer11.

1) Oriented PET resin layer/Oriented nylon layer2) Oriented nylon layer/oriented PET resin layer

To improve the mechanical aptitude (stability when passed throughprocessing machines and a packaging machine) and surface protectingability (heat resistance and electrolyte resistance) of the packagingsheet and to reduce friction between a die and the base layer 11 whenembossing the packaging laminated sheet, it is preferable that the baselayer 11 consists of plural layers and the surface of the base layer 11is coated with a fluorocarbon resin, an acrylic resin or a siliconeresin. The base layer 11 may be any one of the following laminatedfilms.

3) Fluorocarbon resin layer/Oriented PET resin layer (the fluorocarbonresin layer may be a fluorocarbon resin film or a film formed byspreading a liquid fluorocarbon resin in a film and drying the same.)4) Silicone resin layer/Oriented PET resin layer (the silicone resinlayer may be a silicone resin film or a film formed by spreading aliquid silicone resin in a film and drying the same.)5) Fluorocarbon resin layer/Oriented PET resin layer/Oriented nylonlayer6) Silicone resin layer/Oriented PET resin layer/Oriented PET resinlayer/Oriented nylon layer7) Acrylic resin layer/Oriented nylon layer (the acrylic resin layer maybe an acrylic resin film or a film formed by spreading an acrylic resinand drying the same.)

The base layer 11 is laminated to the aluminum foil 12 by a drylamination method, an extrusion lamination method or any suitablemethod.

The aluminum foil 12, which will be also referred to as a barrier layer12, of the polymer battery module packaging sheet prevents thepenetration of moisture into the polymer battery. To avoid the adverseeffect of pinholes that may be formed in the barrier layer 12, tostabilize the workability (ease of fabricating pouches or embossing) andto provide the barrier layer 12 with pinhole resistance, the barrierlayer 12 has a thickness of 15 μm or above and is formed from a metalfoil, such as an aluminum foil or a nickel foil, having a thickness of15 μm or above, or a film coated with an inorganic compound, such assilicon dioxide or alumina, by evaporation. Preferably, the barrierlayer 12 is an aluminum foil of a thickness in the range of 15 to 80 μm.

The inventors of the present invention made studies to reduce pinholesand to prevent the cracking of an embossed package and found thataluminum having an iron content in the range of 0.3 to 9.0% by weight,preferably, 0.7 to 2.0% by weight is more satisfactory in ductility thanaluminum not containing any iron and an aluminum foil (barrier layer 12)of such aluminum is less subject to the formation of pinholes when thepackaging laminated sheet is bent and is more capable of facilitatingforming the side walls of the embossed package than an aluminum foil ofaluminum not containing any iron. Aluminum foils of aluminum having aniron content less than 0.3% by weight are not satisfactorilypinhole-resistant and do not improve the formability of the packaginglaminated sheet. Aluminum foils of aluminum having an iron contentexceeding 0.9% by weight are unsatisfactory in flexibility and affectadversely to the workability of the packaging laminated sheet in forminga pouch.

The flexibility, stiffness and hardness of an aluminum foil formed bycold rolling are dependent on annealing conditions. The presentinvention prefers rather soft, slightly or completely annealed aluminumfoils to those treated by a hardening process and not annealed.

Annealing conditions that affect the flexibility, stiffness and hardnessof aluminum foils may be properly determined according to the requiredworkability (ease of forming pouches or embossed packages) of thepackaging laminated sheet. For example, to prevent the formation ofcreases or pinholes in making a package by an embossing process, aslightly or completely annealed, soft aluminum foils are preferable tounannealed, hard aluminum foils.

The inventors of the present invention found that the dissolution andcorrosion of the inner surface of the aluminum foil, particularly, analuminum oxide film coating the aluminum foil, by hydrogen fluorideproduced by the interaction of the electrolyte of the polymer batteryand moisture can be prevented, the adhesive property (wettability) ofthe surfaces of the aluminum foil can be improved and the adhesivestrength between the aluminum foil and the adhesive resin layer whenforming the packaging laminated sheet can be stabilized by formingacid-resistant coating on the surfaces of the aluminum foil andsubjecting the packaging laminated sheet to an adhesive strengthenhancing process.

Component layers of the layer on the inner surface of the aluminum foil12 of the packaging laminated sheet are formed by a coextrusionlamination method. The adhesive resin layer 13 and the innermost layer14 are formed and are bonded to the surface of the aluminum foil coatedwith the chemical conversion coating by coextrusion. The innermostlayers 14 can be bonded together by heat-sealing. Desirably, theinnermost layer 14 is a film of a material having necessary propertiesincluding a heat-resistant property, a moistureproof property andpress-formability, such as a cast PP resin (CPP resin). A PPa resin filmand a cast PP resin film are coextruded in a laminated film onto thesurface of the aluminum foil coated with the chemical conversion coatingwith the PPa resin film in contact with the aluminum foil.

The packaging laminated sheet i.e., the polymer battery module packagingsheet, may be provided, in addition to the base layer 11, the barrierlayer 12, the adhesive resin layer 13 and the innermost layer (CPP resinlayer) 14, an intermediate layer sandwiched between the barrier layer 12and the adhesive resin layer 13. The intermediate layer is employed toenhance the strength of the packaging laminated sheet and to improve andstabilize the barrier property of the packaging laminated sheet.

The inventors of the present invention found through studies that asatisfactory packaging laminated sheet can be formed by using analuminum foil having opposite surfaces coated with the chemicalconversion coatings 15 a and 15 b formed by chemical conversiontreatment as the barrier layer 12 as shown in FIGS. 5( b) and 5(c). Thechemical conversion treatment forms acid-resistant films of a phosphate,a chromate, a fluoride or a triazine thiol compound. Thus the separationof the aluminum foil 12 and the base layer 11 during an embossingprocess can be prevented, the dissolution and corrosion of the surfacesof the aluminum foil 12, particularly, aluminum oxide films coating thealuminum foil, by hydrogen fluoride produced by the interaction of theelectrolyte of the polymer battery module and moisture can be prevented,the adhesive property (wettability) of the surface of the aluminum foil12 is improved, the separation of the base layer and the aluminum foilduring heat-sealing can be prevented and the separation of the aluminumfoil and the base layer during embossing can be prevented.

It was found through experimental chemical conversion treatment usingvarious substances that chemical conversion treatment method using amixture of a phenolic resin, trivalent chromium fluoride and phosphoricacid has satisfactory effect. The weight per unit area of the film is onthe order of 10 mg/m² (dry weight).

When the packaging laminated sheet is intended for use for formingpouches, only one surface on the side of the innermost layer of thealuminum foil 12 needs to be processed by the chemical conversiontreatment.

When both the surfaces of the aluminum foil are processed by thechemical conversion treatment, the separation of the aluminum foil 12and the base layer 11 can be prevented when embossing the packaginglaminated sheet. The packaging laminated sheet including the aluminumfoil 12 having both the surfaces processed by the chemical conversiontreatment may be used for forming pouches.

When manufacturing the packaging laminated sheet of the presentinvention, the opposite surfaces of the aluminum foil 12, i.e., thebarrier layer, are processed by chemical conversion treatment the baselayer is bonded to one of the surfaces of the aluminum foil 12 by a drylamination method, and molten resin films of resins for forming theadhesive resin layer 13 and the innermost layer 14 are extruded by acoextrusion lamination method onto the other surface of the aluminumfoil 12.

Although the productivity of the laminating process using coextrusion issatisfactory, the adhesion of the adhesive resin layer 13 to thechemical conversion coating of the aluminum foil is not as high as anadhesion required of the packaging laminated sheet when a film of a PParesin for forming the adhesive resin layer 13 and a film of a CPP resinfor forming the innermost layer 14 are coextruded onto the surfacetreated by chemical conversion treatment of the aluminum foil. Theinventors of the present invention found through earnest studies thatthe adhesive strength between the adhesive resin layer and the chemicalconversion coating can be increased by heating the packaging laminatedsheet as formed. The packaging laminated sheet may be heated by any oneof a contact heating method using a hot roller, a hot air heating methodusing hot air and an infrared heating method using near or far infraredrays, provided that the adhesive resin forming the adhesive resin layercan be heated at a temperature not lower than the softening pointthereof.

Cast PP resin films are suitable for forming the innermost layer 14.Cast PP resin films are satisfactory in heat-sealability, have excellentprotective properties including moistureproof and heat-resistantproperties required of the innermost layer 14, facilitate a laminationprocess and an embossing process for embossing the packaging laminatedsheet.

Possible resins for forming the cast PP resin film are homo type PPresins having a melting point of 150° C. or above, ethylene-propylenecopolymers (random copolymers) having a melting point of 130° C. orabove, ethylene-butene-propylene terpolymers. Those resins may be usedeither individually or in combination. The innermost layer 14 may beeither a single-layer film or a multilayer film.

The PP resin forming the cast PP resin film may contain 5% or above of alow-crystalline ethylene-butene copolymer, a low-crystallinepropylene-butene copolymer, an amorphous ethylene-propylene copolymer oran amorphous propylene-ethylene copolymer to give the packaginglaminated sheet flexibility to improve the folding property of thepackaging laminated sheet and to prevent the cracking of the packaginglaminated sheet during forming.

Possible resins for forming the bonding layer 16 used for bondingtogether the base layer 11 and the barrier layer 12 by dry laminationare polyester resins, polyethylene imine resins, polyether resins,cyanoacrylate resins, urethane resins, organic titanium compounds,polyether-urethane resins, epoxy resins, polyester-urethane resins,imide resins, isocyanate resins, polyolefin resins, silicone resins andthe like.

Examples

Packaging laminated sheets in examples of the third embodiment will bedescribed hereinafter.

The chemical conversion treatment used an aqueous solution of a phenolicresin, a trivalent chromium fluoride compound and phosphoric acid as aprocessing liquid. The processing liquid was applied to the surface ofthe aluminum foil by a roll coating method in a film, and the film wasbaked at 180° C. or above. The weight per unit area of the film was 10mg/m² (dry weight).

Packaging laminated sheets in Example 3-1 and Comparative examples 3-1and 3-3 were subjected to heat-sealing to form 50 mm×80 mm pillow typepouches and polymer battery modules were sealed in the pillow typepouches, respectively.

Packaging laminated sheets in Example 3-2 and Comparative examples 3-2and 3-4 were subjected to an embossing process to form embossed packageseach having a hollow part of 30 mm×50 mm×3.5 ram. The formability of thepackaging laminated sheets was evaluated.

Adhesive films of unsaturated carboxylic acid graft random polypropyleneresin having a thickness of 20 μm were wound around parts to becontiguous with the pouch or the embossed package of the tabs of polymerbattery modules, and the pouch or the embossed package was heat-sealed.

Example 3-1 Pouch

Both the surfaces of a 20 μm thick aluminum foil were subjected tochemical conversion treatment. An oriented polyester film was laminatedto one of the surfaces of the aluminum foil by a dry lamination method.A laminated film of a 20 μm thick molten resin film of a PPa resinhaving a softening point of 120° C. and a 30 μm thick molten resin filmof a PP resin was bonded to the other surface of the aluminum foil by acoextrusion lamination method such that the molten resin film of the PParesin is in contact with the surface of the aluminum foil. A packaginglaminated sheet thus formed was heated so that the surfaces of thealuminum foil were heated at 150° C. to obtain the packaging laminatedsheet in Example 3-1.

Example 3-2 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick molten resin film of a PPa resin havinga softening point of 120° C. and a 30 μm thick molten resin film of a PPresin was bonded to the other surface of the aluminum foil by acoextrusion lamination method such that the molten resin film of the PParesin is in contact with the aluminum foil. A packaging laminated sheetthus formed was heated so that the surfaces of the aluminum foil wereheated at 150° C. to obtain a packaging laminated sheet in Example 3-2.

Comparative Example 3-1 Pouch

Both the surfaces of a 20 μm thick aluminum foil were subjected tochemical conversion treatment. An oriented polyester film was laminatedto one of the surfaces of the aluminum foil by a dry lamination method.A laminated film of a 20 μm thick molten resin film of a PPa resinhaving a softening point of 120° C. and a 30 μm thick molten resin filmof a PP resin was bonded to the other surface of the aluminum foil by acoextrusion lamination method such that the molten resin film of the PParesin is in contact with the surface of the aluminum foil to obtain apackaging laminated sheet in Comparative example 3-1.

Comparative Example 3-2 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick molten resin film of a PPa resin havinga softening point of 120° C. and a 30 μm thick molten resin film of a PPresin was bonded to the other surface of the aluminum foil by acoextrusion lamination method such that the molten resin film of the PParesin is in contact with the aluminum foil to obtain a packaginglaminated sheet in Comparative example 3-2.

Comparative Example 3-3 Pouch

An oriented polyester film was laminated to one of the surfaces of a 40μm thick aluminum foil by a dry lamination method. A laminated film of a20 μm thick molten resin film of a PPa resin having a softening point of120° C. and a 30 μm thick molten resin film of a PP resin was bonded tothe other surface of the aluminum foil by a coextrusion laminationmethod such that the molten resin film of the PPa resin is in contactwith the aluminum foil to obtain a packaging laminated sheet inComparative example 3-3.

Comparative Example 3-4 Embossed Package

A 25 μm thick nylon film was laminated to one of the surfaces of a 40 μmthick aluminum foil by a dry lamination method. A laminated film of a 20μm thick molten resin film of a PPa resin having a softening point of120° C. and a 30 μm thick molten resin film of a PP resin was bonded tothe other surface of the aluminum foil by a coextrusion laminationmethod such that the molten resin film of the PPa resin is in contactwith the aluminum foil to complete a packaging laminated sheet inComparative example 3-4.

Embossing and Packaging

Pouches were formed by processing the packaging laminated sheets inExample 3-1 and Comparative examples 3-1 and 3-3, embossed packages wereformed by press-forming the packaging laminated sheets in Example 3-2and Comparative examples 3-2 and 3-4, and polymer battery modules werepackaged in the pouches and the embossed packages to form polymerbatteries. The polymer batteries were evaluated by the followingmethods.

Evaluating Methods

1) Delamination during Forming

Samples were inspected for the separation of the base layer and thealuminum foil immediately after forming.

2) Chemical Resistance Test

Samples were inspected for the separation of the aluminum foil and theinnermost film, i.e., a cast PP resin film, after keeping the samples inan atmosphere of 60° C. and 90% RH in a thermostat for seven days.

3) Delamination during Heat-Sealing Process

Samples were inspected for the separation of the innermost layer and thealuminum foil immediately after heat-sealing.

Results

The packaging laminated sheets in Examples 3-1 and 3-2 were notdelaminated by embossing and heat-sealing. The packaging laminatedsheets in Comparative examples 3-1 and 3-2 were not delaminated byheat-sealing. The packaging laminated sheet in Comparative example 3-2was not delaminated by embossing. All the hundred sample packaginglaminated sheets in Comparative examples 3-1 and 3-2 were delaminated,which was not due to the corrosion of the inner surface of the aluminumfoil but was due to the separation of the PPa resin film from thesurface treated by the chemical conversion treatment of the aluminumfoil.

Forty sample packaging laminated sheets out of one hundred samplepackaging laminated sheets in Comparative example 3-3 and forty-sixsample packaging laminated sheets out of one hundred sample packaginglaminated sheets in Comparative example 3-4 were delaminated byheat-sealing. Twenty-two sample packaging laminated sheets out of onehundred sample packaging laminated sheets in Comparative example 3-4were delaminated by embossing. All the one hundred sample packaginglaminated sheets were delaminated due to the corrosion of the innersurface of the aluminum foils caused by the chemical resistance test.

The chemical conversion treatment of the opposite surfaces of thealuminum foil prevents the separation of the base layer and the aluminumfoil during an embossing process and heat-sealing. The separation of thealuminum foil and the innermost layer can be prevented because thesurfaces of the aluminum foil are not corroded by hydrogen fluoride thatmay be produced by interaction between the electrolyte of the polymerbattery module and moisture.

Since the formation of the innermost layer and the lamination of thesame to the aluminum foil can be simultaneously accomplished, thepackaging laminated sheet can be efficiently manufactured. Postheatingcan enhance the adhesive strength between the adjacent layers of thepackaging laminated sheet.

Fourth Embodiment

A packaging laminated sheet, i.e., a polymer battery module packagingsheet, in a fourth embodiment according to the present invention has amoistureproof property, and is resistant to the detrimental effects ofthe polymer battery module and capable of being manufactured at a highproductivity. When forming the packaging laminated sheet, the oppositesurfaces of a barrier layer are subjected to chemical conversiontreatment, a heat-sealable film is laminated to the barrier layer by asandwich lamination method to form a laminated sheet and the laminatedsheet is subjected to a heating process to enhance the adhesive strengthbetween the barrier layer and the heat-sealable film.

The inventors of the present invention made earnest studies to develop apackaging laminated sheet that will not be delaminated by embossing andheat-sealing, is resistant to the detrimental effect of a polymerbattery and has satisfactory properties, found that such a packaginglaminated sheet can be obtained by subjecting both the surfaces of analuminum foil to chemical conversion treatment, forming an adhesiveresin layer by extruding a PPa resin, such as an unsaturated carboxylicacid graft random propylene resin, on the inner surface of the aluminumfoil, bonding a PP resin film to the aluminum foil by the adhesive resinlayer by a sandwich lamination method to form a laminated sheet andsubjecting the laminated sheet to postheating, and have made the presentinvention.

As shown in FIGS. 5( b) and 5(c), a packaging laminated sheet 10, i.e.,a polymer battery module packaging sheet, in the fourth embodiment has,as essential components, a base layer 11, a bonding layer 16, a chemicalconversion coating 15 a, a barrier layer (an aluminum foil) 12, achemical conversion coating 15 b, an adhesive resin layer 13 and aheat-sealable resin layer (innermost layer) 14, such as a PP resin film.The heat-sealable resin layer 14 is bonded to the chemical conversioncoating 15 b with the adhesive resin layer 13 by sandwich lamination.The packaging laminated sheet 10 is subjected to postheating after thesame has been formed to enhance the adhesive strength between theadjacent layers. The adhesive resin layer 13 and the heat-sealable resinlayer 14 constitute an innermost layer.

As shown in FIGS. 5( b) and 5(c), the chemical conversion coatings 15 aand 15 b coat both the surfaces of the aluminum foil 12, respectively,and the heat-sealable resin layer 14 is bonded to the inner surface ofthe barrier 12 with the extruded adhesive resin layer 13 by sandwichlamination. The packaging laminated sheet 10 is subjected to postheatingto heat the same at a temperature not lower than the softening point ofthe resin forming the adhesive resin layers.

As shown in FIGS. 5( b) and 5(c), the packaging laminated sheet 10 hasat least the base layer 11, the chemical conversion coating 15 a, thebarrier layer 12, the chemical conversion coating 15 b, the adhesiveresin layer 13 and the heat-sealable resin layer 14. The heat-sealableresin layer 14 is bonded to the barrier layer 14 by a sandwichlamination method. The heat-sealable resin layer 14 is a nonoriented PPresin film. When the packaging laminated sheet 10 is intended forforming an embossed package body 5 a as shown in FIG. 2, the packaginglaminated sheet 10 must be excellent in formability. Materials of thelayers and processes for bonding the layers will be describedhereinafter.

The base layer 11 is an oriented polyester film or an oriented nylonfilm. Possible polyester resins for forming the base layer 11 are PETresins, PET resins, PEN resins, PBN resins, interpolyester resins, PCresins and the like. Possible nylon resins for forming the base layer 11are polyamide resins including nylon 6, nylon 66, copolymers of nylon 6and nylon 66, nylon 610, polymethaxylilene adipamide (MXD6) and thelike.

When the polymer battery is used on a piece of hardware, the base layer11 comes into direct contact with the piece of hardware. Therefore, itis basically desirable to form the base layer 11 of an intrinsicallyinsulating resin. Since a film forming the base layer 11 has pinholesand pinholes will be formed in the film during processing, the thicknessof the base layer 11 must be 6 μm or above, preferably, in the range of12 to 25 μm.

The base layer 11 may be a laminated film in view of providing the baselayer 11 with pinhole resistance and improved insulating ability.

A laminated film for the base layer 11 includes at least one resin layerconsisting of two or more layers each having a thickness of 6 μm orabove, preferably, in the range of 12 to 25 μm. The following laminatedstructures 1) to 7), not shown, are examples of the laminated base layer11.

1) Oriented PET resin layer/Oriented nylon layer2) Oriented nylon layer/Oriented PET resin layer

To improve the mechanical aptitude (stability when passed throughprocessing machines and a packaging machine) and surface protectingability (heat resistance and electrolyte resistance) of the packagingsheet and to reduce friction between a die and the base layer 11 whenforming the embossed package body 5 a, it is preferable that the baselayer 11 consists of plural layers and the surface of the base layer 11is coated with a fluorocarbon resin, an acrylic resin or a siliconeresin. The base layer 11 may be any one of the following laminatedfilms.

3) Fluorocarbon resin layer/Oriented PET resin layer (the fluorocarbonresin layer may be a fluorocarbon resin film or a film formed byspreading a liquid fluorocarbon resin in a film and drying the same.)4) Silicone resin layer/Oriented PET resin layer (the silicone resinlayer may be a silicone resin film or a film formed by spreading aliquid silicone resin in a film and drying the same.)5) Fluorocarbon resin layer/Oriented PET resin layer/Oriented nylonlayer6) Silicone resin layer/Oriented PET resin layer/Oriented nylon layer7) Acrylic resin layer/Oriented nylon layer (the acrylic resin layer maybe an acrylic resin film or a film formed by spreading an acrylic resinand drying the same.)

The aluminum foil (barrier layer) 12 prevents the penetration ofmoisture into the polymer battery, To avoid the adverse effect ofpinholes that may be formed in the barrier layer 12, to stabilize theworkability (ease of fabricating pouches or embossing) and to providethe barrier layer 12 with pinhole resistance, the barrier layer 12 has athickness of 15 μm or above and is formed from a metal foil, such as analuminum foil or a nickel foil, or a film coated with an inorganiccompound, such as silicon dioxide or alumina, by evaporation.Preferably, the barrier layer 12 is an aluminum foil of a thickness inthe range of 20 to 80 μm.

The inventors of the present invention made studies to reduce pinholesand to prevent the cracking of an embossed package and found thataluminum having an iron content in the range of 0.3 to 9.0% by weight,preferably, 0.7 to 2.0% by weight is more satisfactory in ductility thanaluminum not containing any iron, an aluminum foil of such aluminum isless subject to the formation of pinholes when the packaging laminatedsheet is bent and is more capable of facilitating forming the side wallsof the embossed package than an aluminum foil of aluminum not containingany iron. Aluminum foils of aluminum having an iron content less than0.3% by weight are not satisfactorily pinhole-resistant and do notimprove the formability of the packaging laminated sheet. Aluminum foilsof aluminum having an iron content exceeding 0.9% by weight areunsatisfactory in flexibility and affect adversely to the workability ofthe packaging laminated sheet in forming a pouch.

The flexibility, stiffness and hardness of an aluminum foil formed bycold rolling are dependent on annealing conditions. The presentinvention prefers rather soft, slightly or completely annealed aluminumfoils to those treated by a hardening process and not annealed.

Annealing conditions that affect the flexibility, stiffness and hardnessof aluminum foils may be properly determined according to the requiredworkability (ease of forming pouches or embossed packages) of thepackaging laminated sheet. For example, to prevent the formation ofcreases or pinholes in making a package by an embossing process, a softaluminum foil properly annealed according to the degree of forming maybe used.

The inventors of the present invention found through studies that asatisfactory packaging laminated sheet can be formed when both thesurfaces of the aluminum foil 12 are processed by chemical conversiontreatment. The chemical conversion treatment forms an acid-resistantfilm of a phosphate, a chromate, a fluoride or a triazine thiolcompound. The acid-resistant film prevents the separation of thealuminum foil and the base layer during an embossing process, and thedissolution and corrosion of the surfaces of the aluminum foil,particularly, aluminum oxide films coating the aluminum foil, byhydrogen fluoride produced by the interaction of the electrolyte of thepolymer battery module and moisture, improves the adhesive property(wettability) of the surfaces of the aluminum foil, and prevents theseparation of the aluminum foil and the base layer during an embossingprocess and a heat-sealing process and the separation of the aluminumfoil and the heat-sealable resin layer due to the effect of hydrogenfluoride produced by the interaction of the electrolyte and moisture.

It was found through the examination of various chemical conversiontreatment methods that chemical conversion treatment method using amixture of a phenolic resin, trivalent chromium fluoride and phosphoricacid forms a satisfactory acid-resistant film.

When the packaging laminated sheet is to be used for forming a pouch forcontaining a polymer battery module, only the inner surface of thealuminum foil may be processed by chemical conversion treatment.

When the packaging laminated sheet is to be used for forming an embossedpackage for containing a polymer battery module, both the surfaces ofthe aluminum foil 12 are processed by chemical conversion treatment toprevent the separation of the aluminum foil 12 and the base layer 11during an embossing process. The packaging laminated sheet provided withthe aluminum foil having both the surfaces processed by the chemicalconversion treatment may be used for forming pouches.

When a molten PPa resin is extruded to form the adhesive resin layer 13and the heat-sealable resin layer 14 of a CPP resin is bonded to thealuminum foil by sandwich lamination, the adhesion of the extruded PParesin to the chemical conversion coating formed on the aluminum foil 12is insufficient. If an emulsion of the PPa resin is applied to thechemical conversion coatings 15 a and 15 b by a roll coating method, theemulsion is dried in an emulsion film, the emulsion films are baked at atemperature in the range of 170 to 200° C. and the adhesive resin layer13 of the PPa resin is bonded to the chemical conversion coating 15 b bya sandwich lamination process, the adhesive strength between thechemical conversion coating 15 b and the adhesive resin layer 13 isimproved. However, the emulsion films are baked at a very low bakingspeed and the efficiency of the adhesive resin layer forming process isvery low.

The inventors of the present invention made studies to develop a bondingmethod capable of bonding the adhesive resin layer 13 and the chemicalconversion coating 15 b with stable adhesive strength without applyingthe emulsion of the PPa resin and without baking the film of theemulsion and found that a packaging laminated sheet 10 having thecomponent layers bonded together with desired adhesive strength can beformed by bonding a base layer 11 to one of the surfaces processed bythe chemical conversion treatment of a barrier layer 12 by a drylamination process, bonding a PP resin film for the heat-sealable resinlayer with a PPa resin to the other surface of the barrier layer 12 bysandwich lamination to form the packaging laminated sheet 10 and heatingthe packaging laminated sheet 10 at a temperature not lower than thesoftening point of the PPa resin.

The packaging laminated sheet 10 may be heated by any one of a contactheating method using a hot roller, a hot air heating method using hotair and an infrared heating method using near or far infrared rays,provided that the PPa resin can be heated at a temperature not lowerthan the softening point thereof.

The packaging laminated sheet 10 may have, in addition to the base layer11, the barrier layer 12, the adhesive resin layer 13 and theheat-sealable resin layer 14 of a CPP resin, an intermediate layersandwiched between the barrier layer 12 and the heat-sealable resinlayer 14. The intermediate layer is used to enhance the strength of thepackaging laminated sheet to improve and stabilize barrier property.

The component layers of the packaging laminated sheet 10 may beprocessed by a surface activating treatment, such as a corona dischargetreatment, a blasting treatment, an oxidation treatment or ozonetreatment, to improve and stabilize film forming property, laminationproperty, formability (ease of forming pouches or embossed packages).

A CPP resin is a suitable material for forming the heat-sealable layer14. Films of a CPP resin can be easily bonded together by heat-sealing,meet protective properties including moistureproof property and heatresistance required of the heat-sealable resin layer of a polymerbattery module packaging sheet, and have desirable properties suitablefor lamination and embossing.

Possible resins for forming the CPP resin film are (1) homo type PPresins having a melting point of 150° C. or above, (2)ethylene-propylene copolymers (random copolymers) having a melting pointof 130° C. or above, (3) ethylene-butene-pro-pylene terpolymers. Thoseresins may be used either individually or in combination. Theheat-sealable resin layer 14 may be either a single-layer film or amultilayer film.

The CPP resin may contain 5% or above of a low-crystallineethylene-butene copolymer having a density of 900 kg/m³ or below, alow-crystalline propylene-butene copolymer, an amorphousethylene-propylene copolymer or an amorphous pro-pylene-ethylenecopolymer to form a flexible film and to improve fold resistance and toprevent the cracking of the laminated sheet during a forming process.

Desirably, the base layer 11 is bonded to the chemical conversioncoating 15 a of the barrier layer 12 by a dry lamination method.

Possible adhesive resins for forming the bonding layer 16 for bondingthe base layer 11 to the surface processed by the chemical conversiontreatment of the aluminum foil 12 are polyester resins, polyethyleneimine resins, polyether resins, cyanoacrylate resins, urethane resins,organic titanium compounds, polyether-urethane resins, epoxy reins,polyester-urethane resins, imide resins, isocyanate resins, polyolefinresins and silicone resins.

Examples

Examples of the packaging laminated sheet in the fourth embodiment willbe described.

The chemical conversion treatment used an aqueous solution of a phenolicresin, a trivalent chromium fluoride compound and phosphoric acid as aprocessing liquid. The processing liquid was applied to the surface ofthe aluminum foil by a roll coating method in a film, and the film wasbaked at 180° C. or above. The weight per unit area of the film was 10mg/m² (dry weight).

Packaging laminated sheets in Examples 4-1 and Comparative examples 4-1and 4-3 were subjected to heat-sealing to form 50 mm×80 mm pillow typepouches and polymer battery modules were sealed in the pillow typepouches, respectively.

Packaging laminated sheets in Example 4-2 and Comparative examples 4-2and 4-4 were subjected to an embossing process to form embossed packageseach having a hollow part of 30 mm×50 mm×3.5 mm. The formability of thepackaging laminated sheets was evaluated.

Adhesive films of unsaturated carboxylic acid graft random polypropyleneresin having a thickness of 20 μm were wound around parts to becontiguous with the pouch or the embossed package of the tabs of polymerbattery modules, and the pouch or the embossed package was heat-sealed.

Example 4-1 Pouch

Both the surfaces of a 20 μm thick aluminum foil were subjected tochemical conversion treatment. A 16 μm thick oriented polyester film waslaminated to one of the surfaces of the aluminum foil by a drylamination method. A laminated film of a 20 μm thick molten resin filmof a PPa resin having a softening point of 120° C. and a 30 μm thickfilm of a PP resin was bonded to the other surface of the aluminum foilby sandwich lamination. A packaging laminated sheet thus formed washeated so that the surfaces of the aluminum foil were heated at 150° C.to obtain the packaging laminated sheet in Example 4-1.

Example 4-2 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick molten resin film of a PPa resin havinga softening point of 120° C. and a 30 μm thick film of a PP resin wasbonded to the other surface of the aluminum foil by sandwich lamination.A packaging laminated sheet thus formed was heated so that the surfacesof the aluminum foil were heated at 150° C. to obtain a packaginglaminated sheet in Example 4-2.

Comparative Example 4-1 Pouch

Both the surfaces of a 20 μm thick aluminum foil were subjected tochemical conversion treatment. A 12 μm thick oriented polyester film waslaminated to one of the surfaces of the aluminum foil by a drylamination method. A laminated film of a 20 μm thick molten resin filmof a PPa resin having a softening point of 120° C. and a 30 μm thickfilm of a PP resin was bonded to the other surface of the aluminum toobtain a packaging laminated sheet in Comparative example 4-1.

Comparative Example 4-2 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by dry lamination. A laminatedfilm of a 20 μm thick molten resin film of a PPa resin having asoftening point of 120° C. and a 30 μm thick film of a PP resin wasbonded to the other surface of the aluminum foil by sandwich laminationto obtain a packaging laminated sheet in Comparative example 4-2.

Comparative Example 4-3 Pouch

An oriented polyester film was laminated to one of the surfaces of a 20μm thick aluminum foil by a dry lamination method. A laminated film of a20 μm thick molten resin film of a PPa resin having a softening point of120° C. and a 30 μm thick film of a PP resin was bonded to the othersurface of the aluminum foil by sandwich lamination. A packaginglaminated sheet thus formed was heated, such that the surfaces of thealuminum foil were heated at 150° C. to obtain a packaging laminatedsheet in Comparative example 4-3.

Comparative Example 4-4 Embossed Package

A 25 μm thick nylon film was laminated to one of the surfaces of a 40 μmthick aluminum foil by a dry lamination method. A laminated film of a 20μm thick molten resin film of a PPa resin having a softening point of120° C. and a 30 μm thick film of a PP resin was bonded to the othersurface of the aluminum foil by sandwich lamination. A packaginglaminated sheet thus formed was heated such that the surfaces of thealuminum foil were heated at 150° C. to obtain a packaging laminatedsheet in Comparative example 4-4.

Embossing and Packaging

Pouches were formed by processing the packaging laminated sheets inExample 4-1 and Comparative examples 4-1 and 4-3, embossed packages wereformed by press-forming the packaging laminated sheets in Example 4-2and Comparative examples 4-2 and 4-4, and polymer battery modules werepackaged in the pouches and the embossed packages to form polymerbatteries. The polymer batteries were evaluated by the followingmethods.

Evaluating Methods

1) Delamination during Forming

Samples were inspected for the separation of the base layer and thealuminum foil immediately after forming.

2) Chemical Resistance Test

Samples were inspected for the separation of the aluminum foil and theinnermost resin film, i.e., the PP resin film, after keeping the samplesin an atmosphere of 60° C. and 90% RH in a thermostat for seven days.

3) Delamination during Heat-sealing Process

Samples were inspected for the separation of the innermost layer and thealuminum foil immediately after heat-sealing.

Results

The packaging laminated sheets in Examples 4-1 and 4-2 were notdelaminated by embossing and heat-sealing.

The packaging laminated sheets in Comparative examples 4-1 and 4-2 werenot delaminated by heat-sealing. The packaging laminated sheet inComparative example 4-2 was not delaminated by embossing. Theheat-sealable resin layers of all the hundred sample packaging laminatedsheets in Comparative examples 4-1 and 4-2 were separated from thealuminum foils, which was not due to the corrosion of the inner surfaceof the aluminum foil but was due to the separation of the PPa resin filmfrom the surface treated by the chemical conversion treatment of thealuminum foil.

Forty sample packaging laminated sheets out of one hundred samplepackaging laminated sheets in Comparative example 4-3 and forty-sixsample packaging laminated sheets out of one hundred sample packaginglaminated sheets in Comparative example 4-4 were delaminated byheat-sealing. Twenty-two sample packaging laminated sheets out of onehundred sample packaging laminated sheets in Comparative example 4-4were delaminated by embossing. All the one hundred sample packaginglaminated sheets were delaminated due to the corrosion of the innersurface of the aluminum foil caused by the detrimental effect of thepolymer battery modules.

The chemical conversion treatment of the opposite surfaces of thealuminum foil prevents the separation of the base layer and the aluminumfoil during an embossing process and heat-sealing. The separation of thealuminum foil and the innermost layer can be prevented because thesurfaces of the aluminum foil are not corroded by hydrogen fluoride thatmay be produced by interaction between the electrolyte of the polymerbattery module and moisture.

Since the formation of the heat-sealable layer and the lamination of thesame to the aluminum foil can be simultaneously accomplished by asandwich lamination method, the packaging laminated sheet can beefficiently manufactured. Postheating can enhance the adhesive strengthbetween the adjacent layers of the packaging laminated sheet.

Fifth Embodiment

A packaging laminated sheet, i.e., a polymer battery module packagingsheet, in a fifth embodiment according to the present invention has amoistureproof property, and is resistant to the detrimental effects ofthe polymer battery module and capable of being manufactured at a highproductivity. When forming the packaging laminated sheet, the oppositesurfaces of a barrier layer are subjected to chemical conversiontreatment, an adhesive resin layer and an inner resin layer are formedby a coextrusion lamination method on the inner surface to be in contactwith the polymer battery module of the barrier layer to form a laminatedsheet and the laminated sheet is subjected to a heating process toenhance the adhesive strength between the barrier layer and thelaminated sheet.

The inventors of the present invention made earnest studies to develop apackaging laminated sheet that will not be delaminated by embossing andheat-sealing, is resistant to the detrimental effect of a polymerbattery module and has satisfactory properties, found that such apackaging laminated sheet can be obtained by subjecting both thesurfaces of an aluminum foil to chemical conversion treatment, formingan adhesive resin layer by extruding a PPa resin, such as an unsaturatedcarboxylic acid graft random propylene resin, on the inner surface ofthe aluminum foil, bonding an innermost layer of anethylene-butene-propylene terpolymer (hereinafter referred to as “T-PPresin”) to the aluminum foil by the adhesive resin layer to form alaminated sheet, and have made the present invention. The inventors ofthe present invention found that the foregoing problems can be solved bya polymer battery module packaging sheet manufacturing method comprisingthe steps of processing the opposite surfaces of an aluminum foil bychemical conversion treatment, forming a laminated sheet by forming alayer of a PPa resin, such as an unsaturated carboxylic acid graftrandom propylene resin, as an adhesive resin layer, and a layer of aterpolymer on the inner surface of the aluminum foil by a coextrusionlamination method to form a laminated sheet, and subjecting thelaminated sheet to a heating process, and have made the presentinvention.

As shown in FIGS. 5( b) and 5(c), a packaging laminated sheet 10, i.e.,a polymer battery module packaging sheet, in the fifth embodiment has,as essential components, a base layer 11, a bonding layer 16, a chemicalconversion coating 15 a, an aluminum foil 12 as a barrier layer, achemical conversion coating 15 b, an adhesive resin layer 13 and aninnermost layer 14, i.e., a film of a terpolymer of ethylene, butene andpropylene. The adhesive resin layer 13 and the innermost layer 14 areformed by a coextrusion lamination method. The packaging laminated sheet10 is subjected to postheating after the same has been formed to enhancethe adhesive strength between the adjacent layers. The adhesive resinlayer 13 and the innermost layer 14 constitute an innermost layer.

As shown in FIGS. 5( b) and 5(c), the chemical conversion coatings 15 aand 15 b coat both the surfaces of the aluminum foil 12 (barrier layer),respectively, and the innermost layer 14 of the T-PP resin is bonded tothe inner surface of the aluminum foil 12 with the extruded adhesiveresin layer 13 by coextrusion. The packaging laminated sheet 10 issubjected to postheating to heat the same at a temperature not lowerthan the softening point of the resin forming the adhesive resin layer.

As shown in FIGS. 5( b) and 5(c), the packaging laminated sheet 10 hasat least the base layer 11, the chemical conversion coating 15 a, thealuminum foil 12, the chemical conversion coating 15 b, the adhesiveresin layer 13 and the innermost layer 14. The adhesive resin layer 13and the innermost layer 14 are formed by a coextrusion laminationmethod. The innermost layer 14 is formed of the T-PP resin. When thepackaging laminated sheet 10 is intended for forming an embossed packagebody 5 a as shown in FIG. 2, the packaging laminated sheet 10 must beexcellent in formability to form the hollow part 7 for holding a polymerbattery module 2. Materials of the layers of the packaging laminatedsheet 10 and processes for bonding the layers will be describedhereinafter.

The base layer 11 is an oriented polyester film or an oriented nylonfilm. Possible polyester resins for forming the base layer 11 are PETresins, PBT resins, PEN resins, PBN resins, interpolyester resins, PCresins and the like. Possible nylon resins for forming the base layer 11are polyamide resins including nylon 6, nylon 66, copolymers of nylon 6and nylon 66, nylon 610, polymethaxylilene adipamide (MXD6) and thelike.

When a polymer battery using the packaging laminated sheet 10 is used ona piece of hardware, the base layer 11 comes into direct contact withthe piece of hardware. Therefore, it is basically desirable to form thebase layer 11 of an intrinsically insulating resin. Since a film formingthe base layer 11 has pinholes and pinholes will be formed in the filmduring processing, the thickness of the base layer 11 must be 6 μm orabove, preferably, in the range of 12 to 25 μm.

The base layer 11 may be a laminated film in view of providing the baselayer 11 with pinhole resistance and improved insulating ability.

A laminated film for the base layer 11 includes at least one resin layerconsisting of two or more layers each having a thickness of 6 μm orabove, preferably, in the range of 12 to 25 μm. The following laminatedstructures 1) to 7), not shown, are examples of the laminated base layer11.

1) Oriented PET resin layer/Oriented nylon layer2) Oriented nylon layer/Oriented PET resin layer

To improve the mechanical aptitude (stability when passed throughprocessing machines and a packaging machine) and surface protectingability (heat resistance and electrolyte resistance) of the packagingsheet and to reduce friction between a die and the base layer 11 whenforming the embossed package body 5 a, it is preferable that the baselayer 11 consists of plural layers and the surface of the base layer 11is coated with a fluorocarbon resin, an acrylic resin or a siliconeresin. The base layer 11 may be any one of the following laminatedfilms.

3) Fluorocarbon resin layer/Oriented PET resin layer (the fluorocarbonresin layer may be a fluorocarbon resin film or a film formed byspreading a liquid fluorocarbon resin in a film and drying the same.)4) Silicone resin layer/Oriented PET resin layer (the silicone resinlayer may be a silicone resin film or a film formed by spreading aliquid silicone resin in a film and drying the same.)5) Fluorocarbon resin layer/Oriented PET resin layer/Oriented nylonlayer6) Silicone resin layer/Oriented PET resin layer/Oriented nylon layer7) Acrylic resin layer/Oriented nylon layer (the acrylic resin layer maybe an acrylic resin film or a film formed by spreading an acrylic resinand drying the same.)

The barrier layer (aluminum foil) 12 prevents the penetration ofmoisture into the polymer battery. To avoid the adverse effect ofpinholes that may be formed in the barrier layer 12, to stabilize theworkability (ease of fabricating pouches or embossing) and to providethe barrier layer 12 with pinhole resistance, the barrier layer 12 has athickness of 15 μM or above and is formed from a metal foil, such as analuminum foil or a nickel foil, or a film coated with an inorganiccompound, such as silicon dioxide or alumina, by evaporation.Preferably, the barrier layer 12 is an aluminum foil of a thickness inthe range of 20 to 80 μm.

The inventors of the present invention made studies to reduce pinholesand to prevent the cracking of an embossed package and found thataluminum having an iron content in the range of 0.3 to 9.0% by weight,preferably, 0.7 to 2.0% by weight is more satisfactory in ductility thanaluminum not containing any iron, an aluminum foil of such aluminum isless subject to the formation of pinholes when the packaging laminatedsheet is bent and is more capable of facilitating forming the side wallsof the embossed package than an aluminum foil of aluminum not containingany iron. Aluminum foils of aluminum having an iron content less than0.3% by weight are not satisfactorily pinhole-resistant and do notimprove the formability of the packaging laminated sheet. Aluminum foilsof aluminum having an iron content exceeding 0.9% by weight areunsatisfactory in flexibility and affect adversely to the workability ofthe packaging laminated sheet in forming a pouch.

The flexibility, stiffness and hardness of an aluminum foil formed bycold rolling are dependent on annealing conditions. The presentinvention prefers rather soft, slightly or completely annealed aluminumfoils to those treated by a hardening process and not annealed.

Annealing conditions that affect the flexibility, stiffness and hardnessof aluminum foils may be properly determined according to the requiredworkability (ease of forming pouches or embossed packages) of thepackaging laminated sheet. For example, to prevent the formation ofcreases or pinholes in making a package by an embossing process, a softaluminum foil properly annealed according to the degree of forming maybe used.

The inventors of the present invention found through studies that asatisfactory packaging laminated sheet can be formed when both thesurfaces of the barrier layer 12 of aluminum are processed by chemicalconversion treatment. The chemical conversion treatment forms anacid-resistant film of a phosphate, a chromate, a fluoride or a triazinethiol compound. The acid-resistant film prevents the separation of thealuminum foil and the base layer during an embossing process, and thedissolution and corrosion of the surfaces of the aluminum foil,particularly, aluminum oxide films coating the aluminum foil, byhydrogen fluoride produced by the interaction of the electrolyte of thepolymer battery module and moisture, improves the adhesive property(wettability) of the surfaces of the aluminum foil, and prevents theseparation of the aluminum foil and the base layer during an embossingprocess and a heat-sealing process and the separation of the aluminumfoil and the heat-sealable resin layer due to the effect of hydrogenfluoride produced by the interaction of the electrolyte and moisture.

It was found through the examination of various chemical conversiontreatment methods that chemical conversion treatment method using amixture of a phenolic resin, trivalent chromium fluoride and phosphoricacid forms a satisfactory acid-resistant film.

When the packaging laminated sheet is to be used for faulting a pouchfor containing a polymer battery module, only the inner surface of thealuminum foil may be processed by chemical conversion treatment.

When the packaging laminated sheet is to be used for forming an embossedpackage for containing a polymer battery module, both the surfaces ofthe aluminum foil 12 are processed by chemical conversion treatment toprevent the separation of the aluminum foil 12 and the base layer 11during an embossing process. The packaging laminated sheet provided withthe aluminum foil having both the surfaces processed by the chemicalconversion treatment may be used for forming pouches.

The layers on the inner side of the barrier layer 12 of the packaginglaminated sheet of the present invention are formed by a coextrusionlamination method using an apparatus shown in FIG. 10. The adhesiveresin layer 13 and the innermost layer 14 are formed by coextrusion andare bonded to the surface processed by the chemical conversion treatmentof the aluminum foil 12. Desirably, the innermost layer 14 is formed ofa T-PP resin having satisfactory physical properties includingheat-sealability, heat resistance, moistureproof property andpress-formability. The PPa resin having high adhesion to the surfaceprocessed by the chemical conversion treatment of the aluminum foil anda T-PP resin are coextruded on the aluminum foil to laminate the PParesin layer to the aluminum foil.

When fabricating the packaging laminated sheet of the present invention,the adhesive resin layer 13 formed on the inner surface treated bychemical conversion treatment of the aluminum foil is formed of a PParesin, such as an unsaturated carboxylic acid graft random polypropyleneresin. The adhesive resin layer 13 of the PPa resin prevents thecorrosion of the aluminum foil 12 and bonds the innermost layer 14 ofthe T-PP resin firmly to the aluminum foil 12.

A laminating method of forming the adhesive resin layer 13 of the PParesin and the innermost layer 14 on the surface processed by thechemical conversion treatment of the aluminum foil 12 by coextrusion isexcellent in productivity. However, the adhesive strength of theadhesive resin layer 13 is insufficient when the packaging laminatedsheet is used for packaging a polymer battery module.

The inventors of the present invention made studies to develop alaminating method capable of laminating layers so that the layers arekept bonded with stable adhesive strength and fabricated a laminatedsheet having component layers bonded with predetermined adhesivestrength by forming the packaging laminated sheet 10 by the steps oflaminating the base layer 11 to one of the surfaces processed by thechemical conversion treatment of the barrier layer 12 by dry lamination,and forming the adhesive resin layer 13 of a PPa resin and the innermostlayer 14 of a T-PP resin on the other surface of the barrier layer 12 bya coextrusion lamination method to form a laminated structure, andheating the laminated structure at a temperature not lower than thesoftening point of the PPa resin forming the adhesive resin layer 13.

The packaging laminated sheet 10 may be heated by any one of a contactheating method using a hot roller, a hot air heating method using hotair and an infrared heating method using near or far infrared rays,provided that the PPa resin forming the adhesive resin layer 13 can beheated at a temperature not lower than the softening point thereof.

A packaging laminated sheet having component layers bonded together withstage adhesive strength can be formed by another method that heats thesurface on the side of the innermost layer 14 of the aluminum foil 12 ata temperature not lower than the softening point of the PPa resinforming the adhesive resin layer 13 when forming the adhesive resinlayer 13 and the innermost layer 14 by coextrusion.

The PPa resin is (1) an acid-modified homopolypropylene resin having aVicat softening point of 115° C. or above and a melting point of 150° C.or above, (2) an ethylene-propylene copolymer (random copolymer) havinga Vicat softening point of 105° C. or above and a melting point of 130°C. or above or (3) a simple polymer or a blended of polymers containinga T-PP resin as a base resin having a melting point of 110° C. or aboveand produced by acid-modified polymerization using an unsaturatedcarboxylic acid.

The PPa resin may contain 5% or above of a low-crystallineethylene-butene copolymer having a density of 900 kg/m³ or below, alow-crystalline propylene-butene copolymer, an amorphousethylene-propylene copolymer, an amorphous pro-pylene-ethylene copolymeror an ethylene-butene-propylene terpolymer to give the PPa resin filmflexibility, to improve bendability and to prevent cracking during aforming process.

Flexibility may be given to the PPa resin to improve the foldability ofthe PPa resin film and to prevent the cracking of the PPa resin filmduring a forming process by adding 5% or above of a T-PP resin(ethylene-butene-pro-pylene terpolymer) to the PPa

The packaging laminated sheet 10 of the present invention may include,in addition to the base layer 11, the barrier layer 12, the adhesiveresin layer 13 and the innermost layer 14 of the T-PP resin, anintermediate layer between the barrier layer 12 and the innermost layer14 to improve the strength of the packaging laminated sheet as a polymerbattery module packaging sheet and to improve and stabilize theimpermeability of the packaging laminated sheet.

The component layers of the packaging laminated sheet 10 may beprocessed by a surface activating treatment, such as a corona dischargetreatment, a blasting treatment, an oxidation treatment or ozonetreatment, to improve and stabilize film forming property, laminationproperty, formability (ease of forming pouches or embossed packages).

T-PP resins are suitable for forming the innermost layer 14 of thepackaging laminated sheet 10. Films of a T-PP resin can be easily bondedtogether by heat-sealing, meet protective properties includingmoistureproof property and heat resistance required of the heat-sealableresin layer of a polymer battery module packaging sheet, and havedesirable properties suitable for lamination and embossing.

Desirably, the innermost layer 14 has a thickness in the range of 30 to100 μm and is formed of a T-PP resin having a melting point of 120° C.or above. Preferably, the innermost layer 14 is a PP resin layercontaining 5% or above of a terpolymer or a multilayer structure havingat least a PP resin layer containing 5% or above of a terpolymer.

Desirably, the base layer 11 is bonded to the chemical conversioncoating 15 a of the barrier layer 12 by a dry lamination method.

The followings are concrete examples of materials forming the componentlayers of the innermost layer.

-   -   (1) Terpolymer    -   (2) Terpolymer+PP resin    -   (3) Terpolymer/LLDPE/terpolymer    -   (4) Terpolymer+PP resin/LLDPE/terpolymer/PP resin    -   (5) Terpolymer+PP resin/PP resin/terpolymer+PP resin    -   (6) Terpolymer+PP resin/PP resin+LLDPE/terpolymer+PP resin    -   (7) Terpolymer+PP resin/PP resin+terpolymer/terpolymer+PP resin        where “+” denotes blending, “/” indicates coextrusion,        terpolymer content is 5% or above and the PP resin is of a        random polymerization type.

The T-PP resin may contain 5% or above of a low-crystallineethylene-butene copolymer having a density of 900 kg/m³ or below, alow-crystalline propylene-butene copolymer, an amorphousethylene-propylene copolymer or an amorphous propylene-ethylenecopolymer to give the T-PP resin film flexibility, to improvebendability and to prevent cracking during a forming process.

Desirably, the base layer 11 of the packaging laminated sheet of thepresent invention is bonded to the surface processed by the chemicalconversion treatment (coating 15 a) of the barrier layer 12 by a drylamination method.

Possible adhesive resins for forming the bonding layer 16 for bondingthe base layer 11 to the surface of the aluminum foil 12 processed bythe chemical conversion treatment are polyester resins, polyethyleneimine resins, polyether resins, cyanoacrylate resins, urethane resins,organic titanium compounds, polyether-urethane resins, epoxy reins,polyester-urethane resins, imide resins, isocyanate resins, polyolefinresins and silicone resins.

Examples

Examples of the packaging laminated sheet in the fifth embodiment willbe described.

The chemical conversion treatment used an aqueous solution of a phenolicresin, a chromium fluoride compound and phosphoric acid as a processingliquid. The processing liquid was applied to the surface of the aluminumfoil by a roll coating method in a film, and the film was baked at 180°C. or above. The weight per unit area of the film was 10 mg/m² (dryweight).

Examples of the packaging laminated sheet in the fifth embodiment willbe described.

The packaging laminated sheets in examples and comparative examples used25 μm thick nylon films for forming their base layers and used 40 μmthick aluminum foils for fainting their barrier layers.

The innermost layers of the examples of the present invention containeda T-PP resin (ethylene-butene-propylene terpolymer).

Packaging laminated sheets in examples were subjected to single-sideembossing to form embossed packages each having a hollow part of 30mm×50 mm×3.5 mm. The formability of the packaging laminated sheets wasevaluated.

Examples used a PPa resin produced by acid-modified polymerization usingan unsaturated carboxylic acid and containing a random polypropyleneresin (hereinafter referred to as “RPP resin”) having a softening pointof 105° C. and a melting point of 146° C. as a base resin.

Example 5-1

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method.Each of sample packaging laminated sheets in Example 5-1 was formed bybonding a laminated film of a 20 μm thick Film of a PPa resin as anadhesive resin film and a 30 μm thick film of one of the followingresins (1) to (6) by a coextrusion lamination method to the othersurface of the aluminum foil.

(1) Terpolymer

(2) Terpolymer (5%)+RPP (95%)

(3) Terpolymer (50%)+RPP (50%)

(4) Terpolymer (80%)+RPP (20%)

(5) Terpolymer/RPP/terpolymer

(6) Terpolymer/RPP+LLDPE/terpolymer

where “+” denotes blending, “/” indicates coextrusion, “RPP” denotes arandom polypropylene resin and “LLDPE” denotes a linear low-densitypolyethylene resin. Packaging laminated sheets in Example 5-1 werecompleted by subjecting the laminated sheets to a heating process thatheated the laminated sheets so that the surfaces of the aluminum foilswere heated at 140° C.

Example 5-2

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick molten resin film of a PPa resincontaining 10% of the terpolymer and a 30 μm thick molten resin film ofa blend of 5% of the terpolymer and 95% of a PP resin bonded to theother surface of the aluminum foil by a coextrusion lamination method toobtain sample packaging laminated sheets in Example 5-2.

Example 5-3

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick molten resin film of a PPa resincontaining 50% of the terpolymer and a 30 μm thick molten resin film ofa blend of 5% of the terpolymer and 95% of a PP resin was bonded to theother surface of the aluminum foil by a coextrusion lamination method toobtain sample packaging laminated sheets in Example 5-3.

Comparative Example 5-1

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick molten resin film of a PPa resin and a30 μm thick molten resin film of a homopolypropylene resin having amelting point of 151° C. was bonded to the other surface of the aluminumfoil by a coextrusion lamination method to obtain a laminated sheet. Thelaminated sheets thus formed were heated so that the surfaces of thealuminum foils were heated at 150° C. to complete sample packaginglaminated sheets in Comparative example 5-1.

Comparative Example 5-2

A 25 μm thick nylon film was bonded to one of the surfaces of a 40 μmthick aluminum foil by a dry lamination method. Each of sample packaginglaminated sheets in Comparative example 5-2 was formed by bonding alaminated film of a 20 μm thick resin film of a PPa resin having amelting point of 120° C. as an adhesive resin film and a 30 μm thickfilm of one of the resins (1) to (6) used for forming the samplepackaging laminated sheets in Example 5-1 by a coextrusion laminationmethod to the other surface of the aluminum foil. Laminated structuresthus formed were heated so that the surfaces of the aluminum foils wereheated at 150° C. to complete the packaging laminated sheets inComparative example 5-2.

Embossing and Packaging

The sample packaging laminated sheets were subjected to an embossingprocess to form packages and polymer battery modules were packaged inthe packages to form polymer batteries. The polymer batteries wereevaluated by the following methods.

Evaluating Methods

1) Delamination during Forming

Samples were inspected for the separation of the base layer and thealuminum foil immediately after forming.

2) Chemical Resistance Test

Samples were inspected for the separation of the aluminum foil and theinnermost layer after keeping the samples in an atmosphere of 60° C. and90% RH in a thermostat for seven days.

3) Delamination during Heat-Sealing Process

Samples were inspected for the separation of the innermost layer and thealuminum foil immediately after heat-sealing.

Results

The packaging laminated sheets in Examples 5-1, 5-2 and 5-3 were notdelaminated by embossing and heat-sealing. The aluminum foil and thebase layer of each of the packaging laminated sheets in Examples 5-1,5-2 and 5-3 were not separated. The packaging laminated sheets inExamples 5-1, 5-2 and 5-3 were not delaminated by the chemicalresistance test. Any cracks were not formed in the innermost layers ofthe packaging laminated sheets in Examples 5-1, 5-2 and 5-3 during theembossing process and the bending process.

No problem arose during the embossing process and the heat-sealingprocess in the packaging laminated sheets in Comparative example 5-1 andthe aluminum foil and the base layer of each of the packaging laminatedsheets in Comparative example 5-1 were not separated. The packaginglaminated sheets in Comparative example 5-1 were not delaminated by thechemical resistance test. However, cracks were formed during theembossing process in the innermost layers of all the hundred samples andcracks were formed during the bending process in the innermost layers ofthe forty-six samples out of the hundred samples.

Forty-eight sample packaging laminated sheets out of the hundred samplepackaging laminated sheets in Comparative example 5-2 were delaminatedduring the embossing process and the heat-sealing process. All thehundred sample packaging laminated sheets in Comparative example 5-2were delaminated by the chemical resistance test. Cracks were not formedin all the hundred sample packaging laminated sheets in Comparativeexample 5-2 during the embossing process and the bending process.

The chemical conversion treatment of the opposite surfaces of thealuminum foil prevents the separation of the base layer and the aluminumfoil during an embossing process and heat-sealing. The separation of thealuminum foil and the innermost layer can be prevented because thesurfaces of the aluminum foil are not corroded by hydrogen fluoride thatmay be produced by interaction between the electrolyte of the polymerbattery module and moisture.

The innermost layer of the T-PP resin can be efficiently formed throughthe coextrusion of the PPa resin and the adhesive resin. Postheating canenhance the adhesive strength between the adjacent layers of thepackaging laminated sheet. Thus, the laminated packaging structure ofthe fifth embodiment can be used for packaging polymer battery modules.

Sixth Embodiment

A packaging laminated sheet, i.e., a polymer battery module packagingsheet, in a sixth embodiment according to the present invention has amoistureproof property, and is resistant to the detrimental effects ofthe polymer battery module and capable of being manufactured at a highproductivity. When forming the packaging laminated sheet, the oppositesurfaces of a barrier layer are subjected to chemical conversiontreatment, a heat-sealable film is laminated to the barrier layer by asandwich lamination method to form a laminated sheet and the laminatedsheet is subjected to a heating process to enhance the adhesive strengthbetween the barrier layer and the heat-sealable film.

The inventors of the present invention found that problems in packaginglaminated sheets can be solved by subjecting both the surfaces of analuminum foil to chemical conversion treatment, forming an adhesiveresin layer of a PPa resin, such as an unsaturated carboxylic acid graftrandom propylene resin, on the inner surface of the aluminum foil, andusing a beat-sealable resin layer of a T-PP resin, and have made thepresent invention. The inventors of the present invention found thatproblems in packaging laminated sheets can be solved by a packaginglaminated sheet manufacturing method including the steps of subjectingboth the surfaces of an aluminum foil to chemical conversion treatment,forming an adhesive resin layer of a PPa resin, such as an unsaturatedcarboxylic acid graft random propylene resin, on the inner surface ofthe aluminum foil by extrusion, and forming a T-PP resin film by asandwich lamination method on the adhesive resin layer to form alaminated sheet and subjecting the laminated sheet to postheating andhave made the present invention.

As shown in FIGS. 5( b) and 5(c) a packaging laminated sheet 10, i.e., apolymer battery module packaging sheet, in the sixth embodiment has, asessential components, a base layer 11, a bonding layer 16, a chemicalconversion coating 15 a, an aluminum foil 12 as a barrier layer, achemical conversion coating 15 b, an adhesive resin layer 13 and aheat-sealable resin layer 14, i.e., a film of a T-PP resin. The adhesiveresin layer 13 and the heat-sealable resin layer 14 of the T-PP resinare formed by a sandwich lamination method. The packaging laminatedsheet 10 is subjected to postheating after the same has been formed toenhance the adhesive strength between the adhesive resin layer 13 andthe heat-sealable resin layer 14. The adhesive resin layer 13 and theheat-sealable resin layer 14 constitute an innermost layer.

As shown in FIGS. 5( b) and 5(c), the chemical conversion coatings 15 aand 15 b coat both the surfaces of the aluminum foil 12 (barrier layer),respectively, and the heat-sealable resin layer 14 of the T-PP resin isbonded to the inner surface of the aluminum foil 12 with the extrudedadhesive resin layer 13. The packaging laminated sheet 10 is subjectedto postheating to heat the same at a temperature not lower than thesoftening point of the resin forming the adhesive resin layer.

As shown in FIGS. 5( b) and 5(c), the packaging laminated sheet 10 hasat least the base layer 11, the chemical conversion coating 15 a, thealuminum foil 12, the chemical conversion coating 15 b, the adhesiveresin layer 13 and the heat-sealable resin layer 14. The heat-sealableresin layer 14 is bonded to the aluminum foil 12 by a sandwichlamination method. The heat-sealable resin layer 14 is formed of theT-PP resin. When the packaging laminated sheet 10 is intended forforming an embossed package body 5 a as shown in FIG. 2, the packaginglaminated sheet 10 must be excellent in formability to form the hollowpart 7 for holding a polymer battery module 2. Materials of the layersof the packaging 20, laminated sheet 10 and processes for bonding thelayers will be described hereinafter.

The base layer 11 is an oriented polyester film or an oriented nylonfilm. Possible polyester resins for forming the base layer 11 are PETresins, PBT resins, PEN resins, PBN resins, interpolyester resins, PCresins and the like. Possible nylon resins for forming the base layer 11are polyamide resins including nylon 6, nylon 66, copolymers of nylon 6and nylon 66, nylon 610, polymethaxylilene adipamide (MXD6) and thelike.

When a polymer battery using the packaging laminated sheet 10 is used ona piece of hardware, the base layer 11 comes into direct contact withthe piece of hardware. Therefore, it is basically desirable to form thebase layer 11 of an intrinsically insulating resin. Since a film formingthe base layer 11 has pinholes and pinholes will be formed in the filmduring processing, the thickness of the base layer 11 must be 6 μm orabove, preferably, in the range of 12 to 25 μm.

The base layer 11 may be a laminated film in view of providing the baselayer 11 with pinhole resistance and improved insulating ability.

A laminated film for the base layer 11 includes at least one resin layerconsisting of two or more layers each having a thickness of 6 μm orabove, preferably, in the range of 12 to 25 μm. The following laminatedstructures 1) to 7), not shown, are examples of the laminated base layer11.

1) Oriented PET resin layer/Oriented nylon layer2) Oriented nylon layer/Oriented PET resin layer

To improve the mechanical aptitude (stability when passed throughprocessing machines and a packaging machine) and surface protectingability (heat resistance and electrolyte resistance) of the packagingsheet and to reduce friction between a die and the base layer 11 whenforming an embossed package, it is preferable that the base layer 11consists of plural layers and the surface of the base layer 11 is coatedwith a fluorocarbon resin, an acrylic resin or a silicone resin. Thebase layer 11 may be any one of the following laminated films.

3) Fluorocarbon resin layer/Oriented PET resin layer (the fluorocarbonresin layer may be a fluorocarbon resin film or a film formed byspreading a liquid fluorocarbon resin in a film and drying the same.)4) Silicone resin layer/Oriented PET resin layer (the silicone resinlayer may be a silicone resin film or a film formed by spreading aliquid silicone resin in a film and drying the same.)5) Fluorocarbon resin layer/oriented PET resin layer/Oriented nylonlayer6) Silicone resin layer/Oriented PET resin layer/Oriented nylon layer7) Acrylic resin layer/Oriented nylon layer (the acrylic resin layer maybe an acrylic resin film or a film formed by spreading an acrylic resinand drying the same.)

The barrier layer (aluminum foil) 12 prevents the penetration ofmoisture into the polymer battery. To avoid the adverse effect ofpinholes that may be formed in the barrier layer 12, to stabilize theworkability (ease of fabricating pouches or embossing) and to providethe barrier layer 12 with pinhole resistance, the barrier layer 12 has athickness of 15 μm or above and is formed from a metal foil, such as analuminum foil or a nickel foil, or a film coated with an inorganiccompound, such as silicon dioxide or alumina, by evaporation.Preferably, the barrier layer 12 is an aluminum foil of a thickness inthe range of 20 to 80 μm.

The inventors of the present invention made studies to reduce pinholesand to prevent the cracking of an embossed package and found thataluminum having an iron content in the range of 0.3 to 9.0% by weight,preferably, 0.7 to 2.0% by weight is more satisfactory in ductility thanaluminum not containing any iron, an aluminum foil of such aluminum isless subject to the formation of pinholes when the packaging laminatedsheet is bent and is more capable of facilitating forming the side wallsof the embossed package than an aluminum foil of aluminum not containingany iron. Aluminum foils of aluminum having an iron content less than0.3% by weight are not satisfactorily pinhole-resistant and do notimprove the formability of the packaging laminated sheet. Aluminum foilsof aluminum having an iron content exceeding 0.9% by weight areunsatisfactory in flexibility and affect adversely to the workability ofthe packaging laminated sheet in forming a pouch.

The flexibility, stiffness and hardness of an aluminum foil formed bycold rolling are dependent on annealing conditions. The presentinvention prefers rather soft, slightly or completely annealed aluminumfoils to those treated by a hardening process and not annealed.

Annealing conditions that affect the flexibility, stiffness and hardnessof aluminum foils may be properly determined according to the requiredworkability (ease of forming pouches or embossed packages) of thepackaging laminated sheet. For example, to prevent the formation ofcreases or pinholes in making a package by an embossing process, a softaluminum foil properly annealed according to the degree of forming maybe used.

The inventors of the present invention found through studies that asatisfactory packaging laminated sheet can be formed when both thesurfaces of the barrier layer 12 of aluminum are processed by chemicalconversion treatment. The chemical conversion treatment forms anacid-resistant film of a phosphate, a chromate, a fluoride or a triazinethiol compound. The acid-resistant film prevents the separation of thealuminum foil and the base layer during an embossing process, and thedissolution and corrosion of the surfaces of the aluminum foil,particularly, aluminum oxide films coating the aluminum foil, byhydrogen fluoride produced by the interaction of the electrolyte of thepolymer battery module and moisture, improves the adhesive property(wettability) of the surfaces of the aluminum foil, and prevents theseparation of the aluminum foil and the base layer during an embossingprocess and a heat-sealing process and the separation of the aluminumfoil and the heat-sealable resin layer due to the effect of hydrogenfluoride produced by the interaction of the electrolyte and moisture.

It was found through the examination of various chemical conversiontreatment methods that chemical conversion treatment method using amixture of a phenolic resin, chromium fluoride and phosphoric acid formsa satisfactory acid-resistant film.

When the packaging laminated sheet is to be used for forming a pouch forcontaining a polymer battery module, only the inner surface of thealuminum foil may be processed by chemical conversion treatment.

When the packaging laminated sheet is to be used for forming an embossedpackage for containing a polymer battery module, both the surfaces ofthe aluminum foil 12 are processed by chemical conversion treatment toprevent the separation of the aluminum foil 12 and the base layer 11during an embossing process. The packaging laminated sheet provided withthe aluminum foil having both the surfaces processed by the chemicalconversion treatment may be used for forming pouches.

In the packaging laminated sheet of the present invention, an adhesiveresin layer 13 of a PPa resin, such as an unsaturated carboxylic acidgraft random propylene resin, is formed on the inner surface processedby the chemical conversion treatment of the aluminum foil 12. Theadhesive resin layer 13 of the PPa resin prevents the corrosion of thealuminum foil 12 and stabilizes the adhesion of a heat-sealable resinlayer of a T-PP resin.

The inventors of the present invention made studies to develop alaminating method capable of laminating layers so that the layers arekept bonded with stable adhesive strength and fabricated a laminatedsheet having component layers bonded with predetermined adhesivestrength by forming the packaging laminated sheet 10 by the steps oflaminating the base layer 11 to one of the surfaces processed by thechemical conversion treatment of the barrier layer 12 by dry lamination,and forming the adhesive resin layer 13 of a PPa resin and the innermostlayer 14 of a T-PP resin on the other surface of the barrier layer 12 bya sandwich lamination method to form a laminated structure, and heatingthe laminated structure at a temperature not lower than the softeningpoint of the PPa resin forming the adhesive resin layer 13.

The packaging laminated sheet 10 may be heated by any one of a contactheating method using a hot roller, a hot air heating method using hotair and an infrared heating method using near or far infrared rays,provided that the PPa resin forming the adhesive resin layer 13 can beheated at a temperature not lower than the softening point thereof.

A packaging laminated sheet having component layers bonded together withstable adhesive strength can be formed by another method that heats thesurface on the side of the innermost layer 14 of the aluminum foil 12 ata temperature not lower than the softening point of the PPa resinforming the adhesive resin layer 13 when forming the adhesive resinlayer 13 and the innermost layer 14 by sandwich lamination.

The T-PP resin contains an ethylene-butene-propylene copolymer as a baseresin. The PPa resin is (1) a homo type PPa resin having a Vicatsoftening point of 115° C. or above and a melting point of 150° C. orabove, (2) an ethylene-propylene copolymer (random copolymer) having aVicat softening point of 105° C. or above and a melting point of 130° C.or above or (3) a simple resin or a blended resin containing a PPa resinmodified by an unsaturated carboxylic acid and having a melting point of110° C. or above.

The PPa resin may contain 5% or above of a low-crystallineethylene-butene copolymer having a density of 900 kg/m³ or below, alow-crystalline propylene-butene copolymer, an amorphousethylene-propylene copolymer, an amorphous pro-pylene-ethylene copolymeror an ethylene-butene-propylene terpolymer to give the PPa resin filmflexibility, to improve bendability and to prevent cracking during aforming process.

Flexibility may be given to the PPa resin to improve the foldability ofthe PPa resin film and to prevent the cracking of the PPa resin filmduring a forming process by adding 5% or above of a T-PP resin(ethylene-butene-pro-pylene terpolymer) to the PPa resin.

The packaging laminated sheet 10 of the present invention may include,in addition to the base layer 11, the barrier layer 12, the adhesiveresin layer 13 and the innermost layer 14 of the T-PP resin, anintermediate layer sandwiched between the barrier layer 12 and theinnermost layer 14 to improve the strength of the packaging laminatedsheet as a polymer battery module packaging sheet and to improve andstabilize the impermeability of the packaging laminated sheet.

The component layers of the packaging laminated sheet of the presentinvention may be processed by a surface activating treatment, such as acorona discharge treatment, a blasting treatment, an oxidation treatmentor ozone treatment, to improve and stabilize film forming property,lamination property, formability (ease of forming pouches or embossedpackages).

T-PP resins are suitable for forming the innermost layer (heat-sealableresin layer) 14 of the packaging laminated sheet 10. Films of a T-PPresin can be easily bonded together by heat-sealing, meet protectiveproperties including moistureproof property and heat resistance requiredof the heat-sealable resin layer of a polymer battery module packagingsheet, and have desirable properties suitable for lamination andembossing.

Desirably, the innermost layer 14 has a thickness in the range of 30 to100 μm and is formed of a T-PP resin having a melting point of 120° C.or above. Preferably, the innermost layer 14 is

BO

a PP resin layer containing 5% or above of a terpolymer or a multilayerstructure having at least a PP resin layer containing 5% or above of aterpolymer. The followings are concrete examples of materials formingthe component layers of the innermost layer 14.

-   -   (1) Terpolymer    -   (2) Terpolymer+PP resin    -   (3) Terpolymer/LLDPE/terpolymer    -   (4) Terpolymer+PP resin/LLDPE/terpolymer/PP resin    -   (5) Terpolymer+PP resin/PP resin/terpolymer+PP resin    -   (6) Terpolymer+PP resin/PP resin+LLDPE/terpolymer+PP resin    -   (7) Terpolymer+PP resin/PP resin+terpolymer/terpolymer+PP resin        where “+” denotes blending, “/” indicates coextrusion,        terpolymer content is 5% or above and the PP resin is of a        random polymerization type.

The T-PP resin may contain 5% or above of a low-crystallineethylene-butene copolymer having a density of 900 kg/m³ or below, alow-crystalline propylene-butene copolymer, an amorphousethylene-propylene copolymer or an amorphous propylene-ethylenecopolymer to give the T-PP resin film flexibility, to improvebendability and to prevent cracking during a forming process.

Desirably, the base layer 11 of the packaging laminated sheet of thepresent invention is bonded to the surface processed by the chemicalconversion treatment (coating 15 a) of the barrier layer 12 by a drylamination method.

Possible adhesive resins for forming the bonding layer 16 for bondingthe base layer 11 to the surface processed by the chemical conversiontreatment of the aluminum foil 12 are polyester resins, polyethyleneimine resins, polyether resins, cyanoacrylate resins, urethane resins,organic titanium compounds, polyether-urethane resins, epoxy reins,polyester-urethane resins, imide resins, isocyanate resins, polyolefinresins and silicone resins.

Examples

Examples of the packaging laminated sheet in the sixth embodiment willbe described.

The chemical conversion treatment used an aqueous solution of a phenolicresin, a chromium fluoride compound and phosphoric acid as a processingliquid. The processing liquid was applied to the surface of the aluminumfoil by a roll coating method in a film, and the film was baked at 180°C. or above. The weight per unit area of the film was 10 mg/m² (dryweight).

Examples of the packaging laminated sheet in the sixth embodiment willbe described.

The packaging laminated sheets in examples and comparative examples used25 μm thick nylon films for forming their base layers and used 40 μmthick aluminum foils for forming their barrier layers.

The innermost layers of the examples of the present invention containeda T-PP resin (ethylene-butene-propylene terpolymer).

Packaging laminated sheets in examples were subjected to single-sideembossing to form embossed packages each having a hollow part of 30mm×50 mm×3.5 mm. The formability of the packaging laminated sheets wasevaluated.

Examples used a PPa resin produced by acid-modified polymerization usingan unsaturated carboxylic acid and containing a RPP resin having asoftening point of 105° C. and a melting point of 146° C. as a baseresin.

Example 6-1

Both the surfaces of a 40 un thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method.Each of sample packaging laminated sheets in Example 6-1 was formed bybonding a laminated film of a 20 μm thick Film of a PPa resin as anadhesive resin film and a 30 μm thick film of one of the followingresins (1) to (6) by a sandwich lamination method to the other surfaceof the aluminum foil.

(1) Terpolymer

(2) Terpolymer (5%)+RPP (95%)

(3) Terpolymer (50%)+RPP (50%)

(4) Terpolymer (80%)+RPP (20%)

(5) Terpolymer/PP/terpolymer

(6) Terpolymer/PP+LLDPE/terpolymer

where “+” denotes blending, “/” indicates coextrusion, “RPP” denotes arandom polypropylene resin and “LLDPE” denotes a linear low-densitypolyethylene resin. Packaging laminated sheets in Example 6-1 werecompleted by subjecting the laminated sheets to a heating process thatheated the laminated sheets so that the surfaces of the aluminum foilswere heated at 140° C.

Example 6-2

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick molten resin film of a PPa resincontaining 10% of the terpolymer and a 30 μm thick molten resin film ofa blend of 5% of the terpolymer and 95% of a PP resin was bonded to theother surface of the aluminum foil by a sandwich lamination method toobtain sample packaging laminated sheets in Example 6-2.

Example 6-3

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick molten resin film of a PPa resincontaining 50% of the terpolymer and a 30 μm thick molten resin film ofa blend of 5% of the terpolymer and 95% of a PP resin was bonded to theother surface of the aluminum foil by a sandwich lamination method toobtain sample packaging laminated sheets in Example 6-3.

Comparative Example 6-1

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick molten resin film of a PPa resin and amolten resin film of a cast homopolypropylene resin having a meltingpoint of 151° C. was bonded to the other surface of the aluminum foil bya sandwich lamination method to obtain a laminated sheet. The laminatedsheets thus formed were heated so that the surfaces of the aluminumfoils were heated at 150° C. to complete sample packaging laminatedsheets in Comparative example 6-1.

Comparative Example 6-2

A 25 μM thick nylon film was bonded to one of the surfaces of a 40 μmthick aluminum foil by a dry lamination method. Each of sample packaginglaminated sheets in Comparative example 6-2 was formed by bonding alaminated film of a 20 μm thick resin film of a PPa resin having amelting point of 120° C. as an adhesive resin film and a 30 μm thickfilm of one of the resins (1) to (6) used for forming the samplepackaging laminated sheets in Example 6-1 by a sandwich laminationmethod to the other surface of the aluminum foil. Laminated structuresthus formed were heated so that the surfaces of the aluminum foils wereheated at 150° C. to complete the packaging laminated sheets inComparative example 6-2.

Embossing and Packaging

The sample packaging laminated sheets were subjected to an embossingprocess to form packages and polymer battery modules were packaged inthe packages to form polymer batteries. The polymer batteries wereevaluated by the following methods.

Evaluating Methods

1) Delamination during Forming

Samples were inspected for the separation of the base layer and thealuminum foil immediately after forming.

2) Chemical Resistance Test

Samples were inspected for the separation of the aluminum foil and theinnermost layer after keeping the samples in an atmosphere of 60° C. and90% RH in a thermostat for seven days.

3) Delamination during Heat-Sealing Process

Samples were inspected for the separation of the innermost layer and thealuminum foil immediately after heat-sealing.

Results

The packaging laminated sheets in Examples 6-1, 6-2 and 6-3 were notdelaminated by embossing and heat-sealing. The aluminum foil and thebase layer of each of the packaging laminated sheets in Examples 6-1,6-2 and 6-3 were not separated. The packaging laminated sheets inExamples 6-1, 6-2 and 6-3 were not delaminated by the chemicalresistance test. Any cracks were not formed in the innermost layers ofthe packaging laminated sheets in Examples 6-1, 6-2 and 6-3 during theembossing process and the bending process.

No problem arose during the embossing process and the heat-sealingprocess in the packaging laminated sheets in Comparative example 6-1 andthe aluminum foil and the base layer of each of the packaging laminatedsheets in Comparative example 6-1 were not separated. The packaginglaminated sheets in Comparative example 6-1 were not delaminated by thechemical resistance test. However, cracks were formed during theembossing process in the innermost layers of all the hundred samplepackaging laminated sheets in Comparative example 6-1 and cracks wereformed during the bending process in the innermost layers of thefifty-six sample packaging laminated sheets out of the hundred samplepackaging laminated sheets in Comparative example 6-1.

Forty-five sample packaging laminated sheets out of the hundred samplepackaging laminated sheets in Comparative example 6-2 were delaminatedduring the embossing process and the heat-sealing process. All thehundred sample packaging laminated sheets in Comparative example 6-2were delaminated by the chemical resistance test. Cracks were not formedin all the hundred sample packaging laminated sheets in Comparativeexample 6-2 during the embossing process and the bending process.

The chemical conversion treatment of the opposite surfaces of thealuminum foil prevents the separation of the base layer and the aluminumfoil during an embossing process and heat-sealing. The separation of thealuminum foil and the innermost layer can be prevented because thesurfaces of the aluminum foil are not corroded by hydrogen fluoride thatmay be produced by interaction between the electrolyte of the polymerbattery module and moisture.

The innermost layer of the T-PP resin can be efficiently formed bysandwich lamination using the Film of a PPa resin as an adhesive resinfilm. Postheating can enhance the adhesive strength between the adjacentlayers of the packaging laminated sheet. Thus, the laminated packagingstructure of the sixth embodiment can be used for packaging polymerbattery modules.

Seventh Embodiment

A packaging laminated sheet, i.e., a polymer battery module packagingsheet, in a seventh embodiment according to the present invention has amoistureproof property, and is resistant to the detrimental effects ofthe polymer battery module and capable of being manufactured at a highproductivity. When forming the packaging laminated sheet, the oppositesurfaces of a barrier layer are subjected to chemical conversiontreatment, a base layer is bonded to one of the surfaces of the barrierlayer by a dry lamination method, a laminated film is formed on theother surface of the barrier layer by coextruding molten resin films ofa PPa resin and a PE resin onto the other surface of the barrier layerto form a laminated sheet and the laminated sheet is subjected to aheating process to enhance the adhesive strength between the componentlayers.

The inventors of the present invention made earnest studies to develop apackaging laminated sheet, i.e., a battery module packaging sheet, thatwill not be delaminated by embossing and heat-sealing and hassatisfactory properties required of battery module packaging sheets forpackaging a polymer battery, including chemical resistance to thedetrimental effects of a polymer battery module, found that theforegoing problems can be solved by subjecting both the surfaces of analuminum foil to chemical conversion treatment, forming a resin layer ofa PEa resin, such as an unsaturated carboxylic acid graft linearpolyethylene resin, and a PE resin film on the inner surface of thealuminum foil by a coextrusion lamination method and subjecting alaminated sheet thus formed to postheating and have made the presentinvention.

As shown in FIGS. 5( b) and 5(c), a packaging laminated sheet 10, i.e.,a polymer battery module packaging sheet, in the seventh embodiment has,as essential components, a base layer 11, a bonding layer 16, a chemicalconversion coating 15 a, an aluminum foil (barrier layer) 12, a chemicalconversion coating 15 b, an adhesive resin layer 13 and a heat-sealableresin layer (PE resin layer) 14. The adhesive resin layer 13 and theheat-sealable resin layer 14 are formed by a coextrusion laminationmethod. The packaging laminated sheet 10 is subjected to postheatingafter the same has been formed to enhance the adhesive strength betweenthe component layers. The adhesive resin layer 13 and the heat-sealableresin layer 14 constitute an innermost layer.

As shown in FIGS. 5( b) and 5(c), a method of manufacturing a polymerbattery packaging sheet of the present invention comprises the steps ofcoating both the surfaces of the aluminum foil (barrier layer) 12 withthe chemical conversion coatings 15 a and 15 b, forming the adhesiveresin layer 13 of the PEa resin and the heat-sealable resin layer 14 ofthe PE resin by coextrusion on the inner surface of the aluminum foil 12to form a laminated sheet and heating the laminated sheet by postheatingat a temperature not lower than the softening point of the PEa resinforming the adhesive resin layer.

As shown in FIGS. 5( b) and 5(c), the packaging laminated sheet 10 ofthe present invention has at least the base layer 11, the chemicalconversion coating 15 a, the aluminum foil 12, the chemical conversioncoating 15 b, the adhesive resin layer 13 and the heat-sealable resinlayer 14. The adhesive resin layer 13 and the heat-sealable resin layer14 are formed by a coextrusion lamination method. The heat-sealableresin layer 14 is formed of the PE resin. When the packaging laminatedsheet 10 is intended for forming an embossed package body 5 a as shownin FIG. 2, the packaging laminated sheet 10 must be excellent informability to form the hollow part 7 for holding a polymer batterymodule 2. Materials of the layers of the packaging laminated sheet 10and processes for bonding the layers will be described hereinafter.

The base layer 11 is an oriented polyester film or an oriented nylonfilm. Possible polyester resins for forming the base layer 11 are PETresins, PBT resins, PEN resins, PBN resins, interpolyester resins, PCresins and the like. Possible nylon resins for forming the base layer 11are polyamide resins including nylon 6, nylon 66, copolymers of nylon 6and nylon 66, nylon 610, polymethaxylilene adipamide (MXD6) and thelike.

When a polymer battery using the packaging laminated sheet 10 is used ona piece of hardware, the base layer 11 comes into direct contact withthe piece of hardware. Therefore, it is basically desirable to form thebase layer 11 of an intrinsically insulating resin. Since a film formingthe base layer 11 has pinholes and pinholes will be formed in the filmduring processing, the thickness of the base layer 11 must be 6 m orabove, preferably, in the range of 12 to 25 μm.

The base layer 11 may be a laminated film in view of providing the baselayer 11 with pinhole resistance and improved insulating ability.

A laminated film for the base layer 11 includes at least one resin layerconsisting of two or more layers each having a thickness of 6 μm orabove, preferably, in the range of 12 to 25 μm. The following laminatedstructures 1) to 7), not shown, are examples of the laminated base layer11.

1) Oriented PET resin layer/oriented nylon layer2) Oriented nylon layer/oriented PET resin layer

To improve the mechanical aptitude (stability when passed throughprocessing machines and a packaging machine) and surface protectingability (heat resistance and electrolyte resistance) of the packagingsheet and to reduce friction between a die and the base layer 11 whenforming an embossed package, it is preferable that the base layer 11consists of plural layers and the surface of the base layer 11 is coatedwith a fluorocarbon resin, an acrylic resin or a silicone resin. Thebase layer 11 may be any one of the following laminated films.

3) Fluorocarbon resin layer/Oriented PET resin layer (the fluorocarbonresin layer may be a fluorocarbon resin film or a film formed byspreading a liquid fluorocarbon resin in a film and drying the same.)4) Silicone resin layer/Oriented PET resin layer (the silicone resinlayer may be a silicone resin film or a film formed by spreading aliquid silicone resin in a film and drying the same.)5) Fluorocarbon resin layer/Oriented PET resin layer/Oriented nylonlayer6) Silicone resin layer/Oriented PET resin layer/Oriented nylon layer7) Acrylic resin layer/Oriented nylon layer (the acrylic resin layer maybe an acrylic resin film or a film formed by spreading an acrylic resinand drying the same.)

The barrier layer (aluminum foil) 12 prevents the penetration ofmoisture into the polymer battery. To avoid the adverse effect ofpinholes that may be formed in the barrier layer 12, to stabilize theworkability (ease of fabricating pouches or embossing) and to providethe barrier layer 12 with pinhole resistance, the barrier layer 12 has athickness of 15 μm or above and is formed from a metal foil, such as analuminum foil or a nickel foil, or a film coated with an inorganiccompound, such as silicon dioxide or alumina, by evaporation.Preferably, the barrier layer 12 is an aluminum foil of a thickness inthe range of 20 to 80 μm.

The inventors of the present invention made studies to reduce pinholesand to prevent cracking of an embossed package and found that aluminumhaving an iron content in the range of 0.3 to 9.0% by weight,preferably, 0.7 to 2.0% by weight is more satisfactory in ductility thanaluminum not containing any iron, an aluminum foil of such aluminum isless subject to the formation of pinholes when the packaging laminatedsheet is bent and is more capable of facilitating forming the side wallsof the embossed package than an aluminum foil of aluminum not containingany iron. Aluminum foils of aluminum having an iron content less than0.3% by weight are not satisfactorily pinhole-resistant and do notimprove the formability of the packaging laminated sheet. Aluminum foilsof aluminum having an iron content exceeding 0.9% by weight areunsatisfactory in flexibility and affect adversely to the workability ofthe packaging laminated sheet in forming a pouch.

The flexibility, stiffness and hardness of an aluminum foil formed bycold rolling are dependent on annealing conditions. The presentinvention prefers rather soft, slightly or completely annealed aluminumfoils to those treated by a hardening process and not annealed.

Annealing conditions that affect the flexibility, stiffness and hardnessof aluminum foils may be properly determined according to the requiredworkability (ease of forming pouches or embossed packages of thepackaging laminated sheet. For example, to prevent the formation ofcreases or pinholes in making a package by an embossing process, a softaluminum foil properly annealed according to the degree of forming maybe used.

The inventors of the present invention found through studies that asatisfactory packaging laminated sheet can be formed when both thesurfaces of the barrier layer 12 of aluminum are processed by chemicalconversion treatment. The chemical conversion treatment forms anacid-resistant film of a phosphate, a chromate, a fluoride or a triazinethiol compound. The acid-resistant film prevents the separation of thealuminum foil and the base layer during an embossing process, and thedissolution and corrosion of the surfaces of the aluminum foil,particularly, aluminum oxide films coating the aluminum foil, byhydrogen fluoride produced by the interaction of the electrolyte of thepolymer battery module and moisture, improves the adhesive property(wettability) of the surfaces of the aluminum foil, and prevents theseparation of the aluminum foil and the base layer during an embossingprocess and a heat-sealing process and the separation of the aluminumfoil and the heat-sealable resin layer due to the effect of hydrogenfluoride produced by the interaction of the electrolyte and moisture.

It was found through the examination of various chemical conversiontreatment methods that chemical conversion treatment method using amixture of a phenolic resin, trivalent chromium fluoride and phosphoricacid forms a satisfactory acid-resistant film.

When the packaging laminated sheet is to be used for forming a pouch forcontaining a polymer battery module, only the inner surface of thealuminum foil on the side of the innermost layer 14 may be processed bychemical conversion treatment.

When the packaging laminated sheet is to be used for forming an embossedpackage for containing a polymer battery module, both the surfaces ofthe aluminum foil 12 are processed by chemical conversion treatment toprevent the separation of the aluminum foil 12 and the base layer 11during an embossing process. The packaging laminated sheet provided withthe aluminum foil having both the surfaces processed by the chemicalconversion treatment may be used for forming pouches.

The inventors of the present invention made studies to develop alaminating method capable of laminating layers so that the layers arekept bonded with stable adhesive strength and fabricated a laminatedsheet having component layers bonded with predetermined adhesivestrength by forming the packaging laminated sheet 10 by the steps oflaminating the base layer 11 to one surface processed by chemicalconversion treatment (coating 15 a) of the barrier layer 12 by a drylamination method, and forming the laminated film of the adhesive resinlayer 13 of a PEa resin and the innermost layer 14 of a PE resin on theother surface 15 b processed by the chemical conversion treatment of thebarrier layer 12 by a coextrusion lamination method to form a laminatedstructure, and heating the laminated structure at a temperature notlower than the softening point of the PEa resin forming the adhesiveresin layer 13.

The packaging laminated sheet 10 may be heated by any one of a contactheating method using a hot roller, a hot air heating method using hotair and an infrared heating method using near or far infrared rays,provided that the PEa resin forming the adhesive resin layer 13 can beheated at a temperature not lower than the softening point thereof.

A packaging laminated sheet having component layers bonded together withstable adhesive strength can be formed by another method that heats thesurface on the side of the innermost layer 14 of the aluminum foil 12 ata temperature not lower than the softening point of the PEa resinforming the adhesive resin layer 13 when forming the adhesive resinlayer 13 and the innermost layer 14 by a coextrusion lamination method.

The PEa resin is a simple resin produced by denaturing a base resin suchas (1) a linear low-density polyethylene resin (LLDPE resin) having adensity of 0.91 g/cm³ or above, a Vicat softening point of 80° C. orabove and a melting point of 110° C. or above, (2) a medium-densitypolyethylene resin (IDPE resin) having a density of 0.92 g/cm³ or above,a Vicat softening point of 80° C. or above and a melting point of 115°C. or above or (3) a high-density polyethylene resin (HDPE resin) havinga density of 0.92 g/cm³ or above, a Vicat softening point of 90° C. orabove and a melting point of 125° C. or above by using an unsaturatedcarboxylic acid, or a blend of some of those resins.

The PEa resin forming the adhesive resin layer 13 may contain 5% orabove of a low-crystalline ethylene-butene copolymer having a density of900 kg/m³ or below, a low-crystalline propylene-butene copolymer, anamorphous ethylene-propylene copolymer, an amorphous pro-pylene-ethylenecopolymer or an ethylene-butene-propylene terpolymer to give theadhesive resin layer 13 flexibility, to improve bendability and toprevent cracking during a forming process.

The packaging laminated sheet 10 of the present invention may include,in addition to the base layer 11, the barrier layer 12, the adhesiveresin layer 13 and the innermost layer (heat-sealable resin layer) 14 ofthe PE resin, an intermediate layer sandwiched between the barrier layer12 and the adhesive resin layer 13 to improve the strength of thepackaging laminated sheet 10 as a polymer battery module packaging sheetand to improve and stabilize the impermeability of the packaginglaminated sheet 10.

The component layers of the packaging laminated sheet of the presentinvention may be processed by a surface activating treatment, such as acorona discharge treatment, a blasting treatment, an oxidation treatmentor ozone treatment, to improve and stabilize film forming property,lamination property, formability (ease of forming pouches or embossedpackages).

PE resins are suitable for forming the innermost layer (heat-sealableresin layer) 14 of the packaging laminated sheet 10. Films of a PE resincan be easily bonded together by heat-sealing, meet protectiveproperties including moistureproof property and heat resistance requiredof the heat-sealable resin layer of a polymer battery module packagingsheet, and have desirable properties suitable for lamination andembossing.

The innermost layer (heat-sealable resin layer) 14 is a single film or amultilayer film of (1) a linear low-density polyethylene resin (LLDPEresin) having a density of 0.91 gice or above, a Vicat softening pointof 80° C. or above and a melting point of 110° C. or above, (2) amedium-density polyethylene resin (MDPE resin) having a density of 0.92g/cm³ or above, a Vicat softening point of 80° C. or above and a meltingpoint of 115° C. or above, (3) a high-density polyethylene resin (HDPEresin) having a density of 0.94 gicm³ or above, a Vicat softening pointof 90° C. or above and a melting point of 125° C. or above or a blend ofsome of those resins.

The PE resin may contain 5% or above of a low-crystallineethylene-butene copolymer having a density of 900 kg/m³ or below, alow-crystalline propylene-butene copolymer, an amorphousethylene-propylene copolymer, an amorphous propylene-ethylene copolymeror an ethylene-butene-propylene terpolymer to give the PE resin filmflexibility, to improve bendability and to prevent cracking during aforming process. A PP resin may be added to the PE resin to make thepackaging laminated sheet slide smoothly in an embossing process or apouch forming process.

Desirably, the base layer 11 of the packaging laminated sheet of thepresent invention is bonded to the surface processed by the chemicalconversion treatment (coating 15 a) of the barrier layer 12 by a drylamination method.

Possible adhesive resins for forming the bonding layer 16 for bondingthe base layer 11 to the surface processed by the chemical conversiontreatment (coating 15 a) of the aluminum foil 12 are polyester resins,polyethylene imine resins, polyether resins, cyanoacrylate resins,urethane resins, organic titanium compounds, polyether-urethane resins,epoxy reins, polyester-urethane resins, imide resins, isocyanate resins,polyolefin resins and silicone resins.

Examples

Examples of the packaging laminated sheet in the seventh embodiment willbe described.

The chemical conversion treatment used an aqueous solution of a phenolicresin, a chromium fluoride compound and phosphoric acid as a processingliquid. The processing liquid was applied to the surface of the aluminumfoil by a roll coating method in a film, and the film was baked at 180°C. or above. The weight per unit area of the film was 10 mg/m² (dryweight).

Examples of the packaging laminated sheet in the seventh embodiment willbe described.

Packaging laminated sheets in Example 7-1 and Comparative examples 7-2,7-3 and 7-5 were processed to form 50 mm wide and 80 mm long pillow typepouches. Polymer battery modules were packaged and sealed in the pillowtype pouches, respectively.

Packaging laminated sheets in Comparative examples 7-2, 7-4 and 7-6 wereprocessed to form embossed package bodies each provided with a hollowpart of 30 mm×50 mm×3.5 mm.

A 20 μm thick adhesive film of an unsaturated carboxylic acid graftlinear low-density PE resin was wound around parts of tabs of polymerbattery modules corresponding to heat-sealed parts of the pouches andthe embossed packages.

Example 7-1 Pouch

Both the surfaces of a 20 μm thick aluminum foil were subjected tochemical conversion treatment. A 16 μm thick oriented polyester resinfilm was laminated to one of the surfaces of the aluminum foil by a drylamination method. A laminated film of a 20 μm thick film (adhesiveresin layer) of a PEa resin having a softening point of 90° C. and amelting point of 122° C. and a 30 μm thick film of an LLDPE resin wasformed on the other surface of the aluminum foil by a coextrusionlamination method to faun a laminated sheet. The laminated sheet washeated so that the surfaces of the aluminum foil were heated at 110° C.to obtain sample packaging laminated sheets in Example 7-1.

Comparative Example 7-1 Pouch

Both the surfaces of a 20 μm thick aluminum foil were subjected tochemical conversion treatment. A 12 μm thick polyester resin film waslaminated to one of the surfaces of the aluminum foil by a drylamination method. A laminated film of a 20 μm thick film of a PEa resinhaving a softening point of 90° C. and a melting point of 122° C. (20 μmthick film of an LLDPE resin having a softening point of 115° C. and amelting point of 123° C.) and a 30 μm thick film of an LLDPE resinhaving a softening point of 115° C. and a melting point of 123° C.) wasformed by a coextrusion lamination method on the other surface of thealuminum foil to obtain sample packaging laminated sheets in Comparativeexample 7-1.

Comparative Example 7-2 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick film of a PEa resin (HDPE) having asoftening point of 120° C. and a melting point of 130° C. and a 30 μmthick film of an HDPE resin having a softening point of 125° C. and amelting point of 132° C. was formed on the other surface of the aluminumfoil by a coextrusion lamination method to obtain sample packaginglaminated sheets in Comparative example 7-2.

Comparative Example 7-3 Pouch

A 20 μm thick oriented polyester resin film was laminated to one of thesurfaces of a 20 μm thick aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick film of a PEa resin (LLDPE) having asoftening point of 90° C. and a melting point of 115° C. and a 30 μmthick film of an LLDPE resin having a softening point of 115° C. and amelting point of 123° C. was formed on the other surface of the aluminumfoil to form a laminated sheet. The laminated sheet was heated so thatthe surfaces of the aluminum foil was heated at 130° C. to obtain samplelaminated packaging sheets in Comparative example 7-3.

Comparative Example 7-4 Embossed Package

A 25 μm thick nylon film was bonded to one of the surfaces of a 40 μmthick aluminum foil by a dry lamination method. A laminated film of afilm of a PEa (HDPE) having a softening point of 120° C. and a meltingpoint of 130° C. and a 30 μm thick film of an HDPE resin having asoftening point of 125° C. and a melting point of 132° C. was formed bya coextrusion lamination method to form a laminated sheet. The laminatedsheet was heated so that the surfaces of the aluminum foil were heatedat 150° C. to obtain sample packaging laminated sheets in Comparativeexample 7-4.

Comparative Example 7-5 Pouch

An oriented polyester film was bonded to one of the surfaces of a 20 μmthick aluminum foil by a dry lamination method. A laminated film of a 20μm thick film of a PPa resin having a softening point of 120° C. and a30 μm thick film of a PP resin having a softening point of 140° C. and amelting point of 157° C. was formed on the other surface of the aluminumfoil by a coextrusion lamination method to form a laminated sheet. Thelaminated sheet was heated so that the surfaces of the aluminum foilwere heated at 150° C. to obtain sample packaging laminated sheets inComparative example 7-5.

Comparative Example 7-6 Pouch

An oriented polyester filmwas bonded to one of the surfaces of a 40 μmthick aluminum foil by a dry lamination method. A laminated film of a 20μm thick film of a PPa resin having a softening point of 120° C. and a30 μm thick film of a PP resin having a softening point of 140° C. and amelting point of 157° C. was formed on the other surface of the aluminumfoil by a coextrusion lamination method to form a laminated sheet. Thelaminated sheet was heated so that the surfaces of the aluminum foilwere heated at 150° C. to obtain sample packaging laminated sheets inComparative example 7-6.

Pouch Formation, Embossing and Packaging

The sample packaging laminated sheets in Example 7-1 and Comparativeexamples 7-1, 7-3 and 7-5 were subjected to a pouch forming process toform pouches. The sample packaging laminated sheets in Comparativeexamples 7-2, 7-4 and 7-6 were subjected to an embossing process to formpackages. Polymer battery modules were packaged in the pouches and theembossed packages to form polymer batteries. The polymer batteries wereevaluated by the following methods.

Evaluating Methods

1) Delamination during Forming

Samples were inspected for the separation of the base layer and thealuminum foil immediately after forming.

2) Chemical Resistance Test

Samples were inspected for the separation of the aluminum foil and theinnermost layer after keeping the samples in an atmosphere of 60° C. and90% RH in a thermostat for seven days.

3) Delamination during Heat-Sealing Process

Samples were inspected for the separation of the innermost layer and thealuminum foil immediately after heat-sealing.

4) Low-Temperature Resistance

Each of sample packages was prepared by sealing an object in the packageformed by processing the sample packaging laminated sheet by sealing theopening of the package by a heat-sealing process and the sample packageswere dropped from a height of 50 cm in a cold environment of −40° C.Heat-sealed parts of the packages were examined for cracks.

Results

sample packaging laminated sheets in Examples 7-1 and 7-2 were notdelaminated by embossing, heat-sealing and the effect of the polymerbattery modules. Any cracks were not formed in the heat-sealed parts bylow-temperature resistance tests performed in the cold environment of−40° C.

Sample packaging laminated sheets in Comparative examples 7-1, 7-2, 7-3and 7-5 were not delaminated by heat-sealing. Sample packaging laminatedsheets in Comparative example 7-2 were not delaminated by embossing. Theinnermost layers of all the hundred sample packaging laminated sheets inComparative examples 7-1, 7-2, 7-3 and 7-5 were separated from thealuminum foils, respectively.

Forty sample packaging laminated sheets out of the hundred samplepackaging laminated sheets in Comparative example 7-4 and forty-sixsample packaging laminated sheets out of the hundred sample packaginglaminated sheets in Comparative example 7-6 were delaminated byheat-sealing. All the hundred sample packaging laminated sheets in eachof Comparative examples 7-4 and 7-6 were delaminated by the chemicalresistance test.

Cracks were formed in the heat-sealed parts of the twenty samplepackaging laminated sheets out of the hundred sample packaging sheets ineach of Comparative examples 7-5 and 7-6 when the sample polymerbatteries were dropped from a height of 50 cm in the low-temperatureenvironment of −40° C.

The chemical conversion treatment of the opposite surfaces of thealuminum foil prevents the separation of the base layer and the aluminumfoil during embossing and heat-sealing. The separation of the aluminumfoil and the innermost layer can be prevented because the surfaces ofthe aluminum foil are not corroded by hydrogen fluoride that may beproduced by interaction between the electrolyte of the polymer batterymodule and moisture.

The laminated resin layer of the PEa resin and the PE resin can beefficiently formed by the coextrusion lamination method. Postheating canenhance the adhesive strength between the adjacent layers of thepackaging laminated sheet. Thus, the laminated packaging structure ofthe seventh embodiment can be used for packaging polymer batterymodules.

Eighth Embodiment

A packaging laminated sheet, i.e., a polymer battery module packagingsheet, in an eighth embodiment according to the present invention has amoistureproof property, and is resistant to the detrimental effects ofthe polymer battery module and capable of being manufactured at a highproductivity. When forming the packaging laminated sheet, the oppositesurfaces of a barrier layer are subjected to chemical conversiontreatment, a heat-sealable resin film of a PE resin is laminated to oneof the surfaces of the barrier layer by a sandwich lamination method, toform a laminated sheet and the laminated sheet is subjected to a heatingprocess to enhance the adhesive strength between the component layers.

The inventors of the present invention made earnest studies to develop apackaging laminated sheet, i.e., a polymer battery module packagingsheet, that will not be delaminated by embossing and heat-sealing andhas satisfactory properties required of battery module packaging sheetsfor packaging a polymer battery, including chemical resistance to thedetrimental effects of a polymer battery module, found that theforegoing problems can be solved by subjecting both the surfaces of analuminum foil to chemical conversion treatment, forming a resin layer ofa PEa resin, such as an unsaturated carboxylic acid graft linearpolyethylene resin, and a PE resin film as an adhesive resin layer onthe inner surface of the aluminum foil by a sandwich lamination methodand subjecting a laminated sheet thus formed to postheating and havemade the present invention.

As shown in FIGS. 5( b) and 5(c), a packaging laminated sheet 10, i.e.,a polymer battery module packaging sheet, in the eighth embodiment has,as essential components, a base layer 11, a bonding layer 16, a chemicalconversion coating 15 a, an aluminum foil (barrier layer) 12, a chemicalconversion coating 15 b, an adhesive resin layer 13 and a heat-sealableresin layer (PE resin layer) 14. The adhesive resin layer 13 and theheat-sealable resin layer 14 are formed by a sandwich lamination method.The packaging laminated sheet 10 is subjected to postheating after thesame has been formed to enhance the adhesive strength between thecomponent layers. The adhesive resin layer 13 and the heat-sealableresin layer 14 constitute an innermost layer.

As shown in FIGS. 5( b) and 5(c), the present invention coats both thesurfaces of the aluminum foil (barrier layer) 12 with the chemicalconversion coatings 15 a and 15 b, forms the adhesive resin layer 13 andthe heat-sealable resin layer 14 by sandwich lamination on the innersurface of the aluminum foil 12 to form the laminated sheet 10 and heatsthe laminated sheet 10 by post heating at a temperature not lower thanthe softening point of the PEa resin forming the adhesive resin layer13.

As shown in FIGS. 5( b) and 5(c), the packaging laminated sheet 10 ofthe present invention has at least the base layer 11, the chemicalconversion coating 15 a, the aluminum foil 12, the chemical conversioncoating 15 b, the adhesive resin layer 13 and the heat-sealable resinlayer 14. The adhesive resin layer 13 and the heat-sealable resin layer14 are formed by a coextrusion lamination method. The heat-sealableresin layer 14 is formed by a sandwich lamination method. Theheat-sealable resin layer 14 is a nonoriented PE resin film. When thepackaging laminated sheet 10 is intended for forming an embossed packagebody 5 a as shown in FIG. 2, the packaging laminated sheet 10 must beexcellent in formability to form the hollow part 7 for holding a polymerbattery module 2. Materials of the layers of the packaging laminatedsheet 10 and processes for bonding the layers will be describedhereinafter.

The base layer 11 is an oriented polyester film or an oriented nylonfilm. Possible polyester resins for forming the base layer 11 are PETresins, PBT resins, PEN resins, PBN resins, interpolyester resins, PCresins and the like. Possible nylon resins for forming the base layer 11are polyamide resins including nylon 6, nylon 66, copolymers of nylon 6and nylon 66, nylon 610, polymethaxylilene adipamide (MXD6) and thelike.

When a polymer battery using the packaging laminated sheet 10 is used ona piece of hardware, the base layer 11 comes into direct contact withthe piece of hardware. Therefore, it is basically desirable to form thebase layer 11 of an intrinsically insulating resin. Since a film formingthe base layer 11 has pinholes and pinholes will be formed in the filmduring processing, the thickness of the base layer 11 must be 6 μm orabove, preferably, in the range of 12 to 25 μm.

The base layer 11 may be a laminated film in view of providing the baselayer 11 with pinhole resistance and improved insulating ability.

A laminated film for the base layer 11 includes at least one resin layerconsisting of two or more layers each having a thickness of 6 μm orabove, preferably, in the range of 12 to 25 μm. The following laminatedstructures 1) to 7), not shown, are examples of the laminated base layer11.

1) Oriented PET resin layer/Oriented nylon layer2) Oriented nylon layer/Oriented PET resin layer

To improve the mechanical aptitude (stability when passed throughprocessing machines and a packaging machine) and surface protectingability (heat resistance and electrolyte resistance) of the packagingsheet and to reduce friction between a die and the base layer 11 whenforming an embossed package, it is preferable that the base layer 11consists of plural layers and the surface of the base layer 11 is coatedwith a fluorocarbon resin, an acrylic resin or a silicone resin. Thebase layer 11 may be any one of the following laminated films.

3) Fluorocarbon resin layer/Oriented PET resin layer (the fluorocarbonresin layer may be a fluorocarbon resin film or a film formed byspreading a liquid fluorocarbon resin in a film and drying the same.)4) Silicone resin layer/Oriented PET resin layer (the silicone resinlayer may be a silicone resin film or a film formed by spreading aliquid silicone resin in a film and drying the same.)5) Fluorocarbon resin layer/Oriented PET resin layer/Oriented nylonlayer6) Silicone resin layer/Oriented PET resin layer/Oriented nylon layer7) Acrylic resin layer/Oriented nylon layer (the acrylic resin layer maybe an acrylic resin film or a film formed by spreading an acrylic resinand drying the same.)

The barrier layer (aluminum foil) 12 prevents the penetration ofmoisture into the polymer battery. To avoid the adverse effect ofpinholes that may be formed in the barrier layer 12, to stabilize theworkability (ease of fabricating pouches or embossing) and to providethe barrier layer 12 with pinhole resistance, the barrier layer 12 has athickness of 15 μm or above and is formed from a metal foil, such as analuminum foil or a nickel foil, or a film coated with an inorganiccompound, such as silicon dioxide or alumina, by evaporation.Preferably, the barrier layer 12 is an aluminum foil of a thickness inthe range of 20 to 80 μm.

The inventors of the present invention made studies to reduce pinholesand to prevent the cracking of an embossed package and found thataluminum having an iron content in the range of 0.3 to 9.0% by weight,preferably, 0.7 to 2.0% by weight is more satisfactory in ductility thanaluminum not containing any iron, an aluminum foil of such aluminum isless subject to the formation of pinholes when the packaging laminatedsheet is bent and is more capable of facilitating forming the side wallsof the embossed package than an aluminum foil of aluminum not containingany iron. Aluminum foils of aluminum having an iron content less than0.3% by weight are not satisfactorily pinhole-resistant and do notimprove the formability of the packaging laminated sheet. Aluminum foilsof aluminum having an iron content exceeding 0.90 by weight areunsatisfactory in flexibility and affect adversely to the workability ofthe packaging laminated sheet in forming a pouch.

The flexibility, stiffness and hardness of an aluminum foil formed bycold rolling are dependent on annealing conditions. The presentinvention prefers rather soft, slightly or completely annealed aluminumfoils to those treated by a hardening process and not annealed.

Annealing conditions that affect the flexibility, stiffness and hardnessof aluminum foils may be properly determined according to the requiredworkability (ease of forming pouches or embossed packages) of thepackaging laminated sheet. For example, to prevent the formation ofcreases or pinholes in making a package by an embossing process, a softaluminum foil properly annealed according to the degree of forming maybe used.

The inventors of the present invention found through studies that asatisfactory packaging laminated sheet can be formed when both thesurfaces of the barrier layer 12 of aluminum are processed by chemicalconversion treatment. The chemical conversion treatment forms anacid-resistant film of a phosphate, a chromate, a fluoride or a triazinethiol compound. The acid-resistant film prevents the separation of thealuminum foil and the base layer during an embossing process, and thedissolution and corrosion of the surfaces of the aluminum foil,particularly, aluminum oxide films coating the aluminum foil, byhydrogen fluoride produced by the interaction of the electrolyte of thepolymer battery module and moisture, improves the adhesive property(wettability) of the surfaces of the aluminum foil, and prevents theseparation of the aluminum foil and the base layer during an embossingprocess and a heat-sealing process and the separation of the aluminumfoil and the heat-sealable resin layer due to the effect of hydrogenfluoride produced by the interaction of the electrolyte and moisture.

It was found through the examination of various chemical conversiontreatment methods using various substances that chemical conversiontreatment method using a mixture of a phenolic resin, trivalent chromiumfluoride and phosphoric acid forms a satisfactory acid-resistant film.

When the packaging laminated sheet is to be used for forming a pouch forcontaining a polymer battery module, only the inner surface of thealuminum foil on the side of the innermost layer 14 may be processed bychemical conversion treatment.

When the packaging laminated sheet is to be used for forming an embossedpackage for containing a polymer battery module, both the surfaces ofthe aluminum foil 12 are processed by chemical conversion treatment toprevent the separation of the aluminum foil 12 and the base layer 11during an embossing process. The packaging laminated sheet provided withthe aluminum foil having both the surfaces processed by the chemicalconversion treatment may be used for forming pouches.

The inventors of the present invention made studies to develop alaminating method capable of laminating layers so that the layers arekept bonded with stable adhesive strength without applying and baking aPEa resin, and fabricated a laminated sheet 10 having component layersbonded with predetermined adhesive strength by a method including thesteps of laminating the base layer 11 to one surface 15 a of thesurfaces treated by chemical conversion treatment of the barrier layer12 by a dry lamination method, and forming a laminated film of theadhesive resin layer 13 of a PEa resin and the innermost layer 14 of aPE resin on the other surface 15 b processed by the chemical conversiontreatment of the barrier layer 12 by a sandwich lamination method toform a laminated structure, and heating the laminated structure at atemperature not lower than the softening point of the PEa resin formingthe adhesive resin layer 13.

The packaging laminated sheet 10 may be heated by any one of a contactheating method using a hot roller, a hot air heating method using hotair and an infrared heating method using near or far infrared rays,provided that the PEa resin forming the adhesive resin layer 13 can beheated at a temperature not lower than the softening point thereof.

A packaging laminated sheet having component layers bonded together withstable adhesive strength can be formed by another method that heats thesurface on the side of the innermost layer (heat-sealable resin layer)14 of the aluminum foil 12 at a temperature not lower than the softeningpoint of the PEa resin forming the adhesive resin layer 13 when formingthe adhesive resin layer 13 and the innermost layer 14 by a sandwichlamination method.

The PEa resin is a simple resin produced by denaturing a base resin suchas (1) a linear low-density polyethylene resin (LLDPE resin) having adensity of 0.91 g/cm³ or above, a Vicat softening point of 80° C. orabove and a melting point of 110° C. or above, (2) a medium-densitypolyethylene resin (HDPE resin) having a density of 0.92 g/cm³ or above,a Vicat softening point of 80° C. or above and a melting point of 115°C. or above or (3) a high-density polyethylene resin (HDPE resin) havinga density of 0.92 g/cm³ or above, a Vicat softening point of 90° C. orabove and a melting point of 125° C. or above by using an unsaturatedcarboxylic acid, or a blend of some of those resins.

The PEa resin forming the adhesive resin layer 13 may contain 5% orabove of a low-crystalline ethylene-butene copolymer having a density of900 kg/m³ or below, a low-crystalline propylene-butene copolymer, anamorphous ethylene-propylene copolymer, an amorphous pro-pylene-ethylenecopolymer or an ethylene-butene-propylene terpolymer to give theadhesive resin layer 13 flexibility, to improve bendability and toprevent cracking during a forming process.

The packaging laminated sheet 10 of the present invention may include,in addition to the base layer 11, the barrier layer 12, the adhesiveresin layer 13 and the innermost layer (heat-sealable resin layer) 14,an intermediate layer sandwiched between the barrier layer 12 and theinnermost layer 14 to improve the strength of the packaging laminatedsheet 10 as a polymer battery module packaging sheet and to improve andstabilize the impermeability of the packaging laminated sheet 10.

The component layers of the packaging laminated sheet of the presentinvention may be processed by a surface activating treatment, such as acorona discharge treatment, a blasting treatment, an oxidation treatmentor ozone treatment, to improve and stabilize film forming property,lamination property, formability (ease of forming pouches or embossedpackages).

PE resins are suitable for forming the innermost layer (heat-sealableresin layer) 14 of the packaging laminated sheet 10. Films of a PE resincan be easily bonded together by heat-sealing, meet protectiveproperties including moistureproof property and heat resistance requiredof the heat-sealable resin layer of a polymer battery module packagingsheet, and have desirable properties suitable for lamination andembossing.

The innermost layer (heat-sealable resin layer) 14 is a single film or amultilayer film of (1) a linear low-density polyethylene resin (LLDPEresin) having a density of 0.91 g/cm³ or above, a Vicat softening pointof 80° C. or above and a melting point of 110° C. or above, (2) amedium-density polyethylene resin (MDPE resin) having a density of 0.92g/cm³ or above, a Vicat softening point of 80° C. or above and a meltingpoint of 115° C. or above, (3) a high-density polyethylene resin (HDPEresin) having a density of 0.94 g/cm³ or above, a Vicat softening pointof 90° C. or above and a melting point of 125° C. or above, or a blendof some of those resins.

The PE resin may contain 5% or above of a low-crystallineethylene-butene copolymer having a density of 900 kg/m³ or below, alow-crystalline propylene-butene copolymer, an amorphousethylene-propylene copolymer, an amorphous propylene-ethylene copolymeror an ethylene-butene-propylene terpolymer to give the PE resin filmflexibility, to improve bendability and to prevent cracking during aforming process. A PP resin may be added to the PE resin to make thepackaging laminated sheet slide smoothly in an embossing process or apouch forming process.

Desirably, the base layer 11 of the packaging laminated sheet of thepresent invention is bonded to the surface processed by the chemicalconversion treatment (coating 15 a) of the barrier layer 12 by a drylamination method.

Possible adhesive resins for forming the bonding layer 16 for bondingthe base layer 11 to the surface processed by the chemical conversiontreatment (coating 15 a) of the aluminum foil 12 are polyester resins,polyethylene imine resins, polyether resins, cyanoacrylate resins,urethane resins, organic titanium compounds, polyether-urethane resins,epoxy reins, polyester-urethane resins, imide resins, isocyanate resins,polyolefin resins and silicone resins.

Examples

Examples of the packaging laminated sheet in the eighth embodiment willbe described.

The chemical conversion treatment used an aqueous solution of a phenolicresin, a chromium fluoride compound and phosphoric acid as a processingliquid. The processing liquid was applied to the surface of the aluminumfoil by a roll coating method in a film, and the film was baked at 180°C. or above. The weight per unit area of the film was 10 mg/m² (dryweight).

Examples of the packaging laminated sheet in the eighth embodiment willbe described.

Packaging laminated sheets in Example 8-1 and Comparative examples 8-1,8-3 and 8-5 were processed to form 50 mm wide and 80 mm long pillow typepouches. Polymer battery modules were packaged and sealed in the pillowtype pouches, respectively.

Packaging laminated sheets in Example 8-2 and Comparative examples 8-2,8-4 and 8-6 were processed to form embossed package bodies each providedwith a hollow part of 30 mm×50 mm×3.5 mm.

A 20 μm thick adhesive film of an unsaturated carboxylic acid graftlinear low-density PE resin was wound around parts of tabs of polymerbattery modules corresponding to heat-sealed parts of the pouches andthe embossed packages.

Example 8-1 Pouch

Both the surfaces of a 20 μm thick aluminum foil were subjected tochemical conversion treatment. A 16 μm thick oriented polyester resinfilm was laminated to one of the surfaces of the aluminum foil by a drylamination method. A laminated film of a 20 μm thick film (adhesiveresin layer) of a PEa resin having a softening point of 90° C. and amelting point of 122° C. and a 30 μm thick film of an LLDPE resin havinga softening point of 115° C. and a melting point of 123° C. was formedon the other surface of the aluminum foil by a sandwich laminationmethod to form a laminated sheet. The laminated sheet was heated so thatthe surfaces of the aluminum foil were heated at 110° C. to obtainsample packaging laminated sheets in Example 8-1.

Example 8-2 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick film (adhesive resin layer) of a PEaresin (HDPE resin) having a softening point of 120° C. and a meltingpoint of 130° C. and a 30 μm thick film of an HDPE resin having asoftening point of 125° C. and a melting point of 132° C. was formed onthe other surface of the aluminum foil by a sandwich lamination methodto form a laminated sheet. The laminated sheet was heated so that thesurfaces of the aluminum foil were heated at 140° C. to obtain samplepackaging laminated sheets in Example 8-2.

Comparative Example 8-1 Pouch

Both the surfaces of a 20 μm thick aluminum foil were subjected tochemical conversion treatment. A 12 μm thick oriented polyester resin film was laminated to one of the surfaces of the aluminum foil by a drylamination method. A laminated film of a 20 μm thick film of a PEa resinhaving a softening point of 90° C. and a melting point of 122° C. (LLDPEresin having a softening point of 150° C. and a melting point of 123°C.) and a 30 μm thick film of an LLDPE resin was formed by a sandwichlamination method on the other surface of the aluminum foil to obtainsample packaging laminated sheets in Comparative example 8-1.

Comparative Example 8-2 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. A20 μm thick film of a PEa resin (HDPE) having a softening point of 120°C. and a melting point of 130° C. and a 30 μm thick film of an HDPEresin having a softening point of 125° C. and a melting point of 132° C.were formed on the other surface of the aluminum foil by a sandwichlamination method to obtain sample packaging laminated sheets inComparative example 8-2.

Comparative Example 8-3 Pouch

An oriented polyester resin film was laminated to one of the surfaces ofa 20 μm thick aluminum foil by a dry lamination method. A laminated filmof a 20 μm thick film of a PEa resin (LLDPE) having a softening point of90° C. or above and a melting point of 115° C. and a 30 μm thick film ofan LLDPE resin having a softening point of 115° C. and a melting pointof 123° C. was formed by a sandwich lamination method on the othersurface of the aluminum foil to form a a laminated sheet. The laminatedsheet was heated so that the surfaces of the aluminum foil was heated at130° C. to obtain sample laminated packaging sheets in Comparativeexample 8-3.

Comparative Example 8-4 Embossed Package

A 25 μm, thick nylon film was bonded to one of the surfaces of a 40 μmthick aluminum foil by a dry lamination method. A laminated film of afilm of a PEa (HDPE) having a softening point of 120° C. and a meltingpoint of 130° C. and a 30 μm thick film of an HDPE resin having asoftening point of 125° C. and a melting point of 132° C. was formed bya sandwich lamination method to form a laminated sheet. The laminatedsheet was heated so that the surfaces of the aluminum foil were heatedat 150° C. to obtain sample packaging laminated sheets in Comparativeexample 8-4.

Comparative Example 8-5 Pouch

An oriented polyester film was bonded to one of the surfaces of a 20 μmthick aluminum foil by a dry lamination method. A laminated film of a 20μm thick film of a PPa resin having a softening point of 120° C. and a30 μm thick film of a PP resin having a softening point of 140° C. and amelting point of 157° C. was formed on the other surface of the aluminumfoil by a sandwich lamination method to form a laminated sheet. Thelaminated sheet was heated so that the surfaces of the aluminum foilwere heated at 150° C. to obtain sample packaging laminated sheets inComparative example 8-5.

Comparative Example 8-6 Pouch

An oriented polyester film was bonded to one of the surfaces of a 40 μmthick aluminum foil by a dry lamination method. A laminated film of a 20μm thick film of a PPa resin having a softening point of 120° C. and a30 μm thick film of a PP resin having a softening point of 140° C. and amelting point of 157° C. was formed on the other surface of the aluminumfoil by a sandwich lamination method to form a laminated sheet. Thelaminated sheet was heated so that the surfaces of the aluminum foilwere heated at 150° C. to obtain sample packaging laminated sheets inComparative example 8-6.

Pouch Formation, Embossing and Packaging

The sample packaging laminated sheets in Example 8-1 and Comparativeexamples 8-1, 8-3 and 8-5 were subjected to a pouch forming process toform pouches. The sample packaging laminated sheets in Example 8-2 andComparative examples 8-2, 8-4 and 8-6 were subjected to an embossingprocess to form packages. Polymer battery modules were packaged in thepouches and the embossed packages to form polymer batteries. The polymerbatteries were evaluated by the following methods.

Evaluating Methods

1) Delamination during Forming

Samples were inspected for the separation of the base layer and thealuminum foil immediately after forming.

2) Chemical Resistance Test

Samples were inspected for the separation of the aluminum foil and thePE resin layer after keeping the samples in an atmosphere of 60° C. and90% RH in a thermostat for seven days.

3) Delamination during Heat-Sealing Process

Samples were inspected for the separation of the innermost layer and thealuminum foil immediately after heat-sealing.

4) Low-Temperature Resistance

Each of sample packages was prepared by sealing an object in the packageformed by processing the sample packaging laminated sheet by sealing theopening of the package by a heat-sealing process and the sample packageswere dropped from a height of 50 cm in a cold environment of −40° C.Heat-sealed parts of the packages were examined for cracks.

Results

Sample packaging laminated sheets in Examples 8-1 and 8-2 were notdelaminated by embossing, heat-sealing and the effect of the polymerbattery modules. Any cracks were not formed in the heat-sealed parts bylow-temperature resistance tests performed in the cold environment of−40° C.

Sample packaging laminated sheets in Comparative examples 8-1, 8-2, 8-3and 8-5 were not delaminated by heat-sealing. Sample packaging laminatedsheets in Comparative example 8-2 were not delaminated by embossing. Theinnermost layers of all the hundred sample packaging laminated sheets inComparative examples 8-1, 8-2, 8-3 and 8-5 were separated from thealuminum foils, respectively.

Forty sample packaging laminated sheets out of hundred sample packaginglaminated sheets in Comparative example 8-4 and forty-six samplepackaging laminated sheets out of hundred sample packaging laminatedsheets in Comparative example 8-6 were delaminated by heat-sealing. Allthe hundred sample packaging laminated sheets in each of Comparativeexamples 8-4 and 8-6 were delaminated by the chemical resistance test.

Cracks were formed in the heat-sealed parts of the twenty samplepackaging laminated sheets out of the hundred sample packaging sheets ineach of Comparative examples 8-5 and 8-6 when the sample polymerbatteries were dropped from a height of 50 cm in the low-temperatureenvironment of −40° C.

The chemical conversion treatment of the opposite surfaces of thealuminum foil prevents the separation of the base layer and the aluminumfoil during embossing and heat-sealing. The separation of the aluminumfoil and the innermost layer can be prevented because the surfaces ofthe aluminum foil are not corroded by hydrogen fluoride that may beproduced by interaction between the electrolyte of the polymer batterymodule and moisture.

The laminated resin layer of the PE resin film and the PEa resin layer(adhesive resin layer) can be efficiently formed by the sandwichlamination method. Postheating can enhance the adhesive strength betweenthe adjacent layers of the packaging laminated sheet. Thus, thelaminated packaging structure of the eight embodiment can be used forpackaging polymer battery modules.

Ninth Embodiment

A packaging laminated sheet, i.e., a polymer battery module packagingsheet, in a ninth embodiment according to the present invention has amoistureproof property, and is resistant to the detrimental effects ofthe polymer battery module and capable of being manufactured at a highproductivity. When forming the packaging laminated sheet, the oppositesurfaces of a barrier layer are subjected to chemical conversiontreatment, an innermost layer is formed of an ERRPP resin or a resincontaining an ERRPP resin, the innermost layer and an adhesive resinlayer are laminated by a coextrusion lamination method to form alaminated sheet and the laminated sheet is subjected to a heatingprocess to enhance the adhesive strength between the component layers.

The inventors of the present invention made earnest studies to developsuch a packaging laminated sheet, and found that the foregoing problemscan be solved by subjecting both the surfaces of an aluminum foil tochemical conversion treatment, forming an adhesive resin layer of a PParesin, such as an unsaturated carboxylic acid graft random acid-modifiedpolypropylene resin, on one of the surfaces of the aluminum foil,forming a single-layer or multilayer innermost layer of an ERRPP resinor a resin containing an ERRPP resin, forming a laminated film of theadhesive resin layer and the innermost layer by a coextrusion laminationmethod, and heating the surfaces of the aluminum foil during acoextrusion lamination method or the laminated sheet.

As shown in FIG. 11( a), a packaging laminated sheet 10, i.e., a polymerbattery module packaging sheet, in the ninth embodiment has, asessential components, a base layer 11, a bonding layer 16, a chemicalconversion coating 15 a, an aluminum foil (aluminum layer) 12, achemical conversion coating 15 b, an adhesive resin layer 13 and aheat-sealable resin layer (innermost layer) 14. The adhesive resin layer13 is formed of a PPa resin and the heat-sealable resin layer 14 isformed of an ERRPP resin having an ethylene content in the range of 5%to 10% by mol. The heat-sealable resin layer 14 may consist of innermostresin films 14 a and 14 b as shown in FIG. 11( b). At least either theinnermost resin film 14 a or 14 b may be formed of an ERRPP resin. Theadhesive resin layer 13 and the heat-sealable resin layer 14 constitutean innermost layer.

Referring to FIG. 12, when manufacturing the packaging laminated sheet10 provided with the single-layer heat-sealable resin layer 14, anextruder 31 a extrudes the adhesive resin layer 13, an extruder 31 bextrudes the heat-sealable resin layer 14, is and the adhesive resinlayer 13 and the heat-sealable resin layer 14 are bonded together by acoextrusion die 32 to obtain a molten resin layer 33. The molten resinlayer 33 and a base layer unwound from a roll 37 a are bonded togetheras the same pass between a chill roller 34 and a pressure roller 35 toform the packaging laminated sheet 10. The packaging laminated sheet 10is taken up on a roll 37.

In the coextrusion lamination process or after the packaging laminatedsheet 10 has been completed, the packaging laminated sheet 10 is heatedto enhance the adhesive strength between the chemical conversion coating15 b of the aluminum foil 12 and the adhesive resin layer 13 so that thepackaging laminated sheet 10 meets requirements required of a polymerbattery module packaging sheet. The packaging laminated sheet 10 isheated so that the chemical conversion coating 15 b is heated at atemperature not lower than the softening point of the PPa resin or thepackaging laminated sheet 10 is subject to post heating to heat the sameat a temperature not lower than the softening point of the PPa resin.

As shown in FIG. 11( a) or 11(b), the packaging laminated sheet 10,i.e., the polymer battery module packaging sheet, of the presentinvention has, as essential components, a base layer 11, a chemicalconversion coating 15 a, a barrier layer 12, a chemical conversioncoating 15 b, an adhesive resin layer 13 and a heat-sealable resin layer14. The adhesive resin layer 13 and the heat-sealable resin layer 14 areformed and bonded together by a coextrusion lamination method. An ERRPPresin film forming the heat-sealable layer 14 is a multilayer filmincluding at least one of layers 14 a and 14 b of an ERRPP resin.

Materials of the component layers of the laminated sheet 10 according tothe present invention and methods of laminating the component layerswill be described.

The base layer 11 of the packaging laminated sheet according to thepresent invention is a film of an oriented polyester resin or anoriented nylon resin. Possible polyester resins are PET resins, PBTresins, PEN resins, PBN resins, interpolyester resins, PC resins and thelike. Possible nylons, i.e., polyamide resins, are nylon 6, nylon: 66,copolymers of nylon 6 and nylon 66, nylon 610, polymethaxylileneadipamide (MXD6) and the like.

When the polymer battery is used on a device (hardware), the base layer11 touches the device. Therefore, it is desirable to form the base layer11 of an intrinsically insulating resin. Since a film forming the baselayer 11 has pinholes and pinholes will be formed in the film duringprocessing, the thickness of the base layer 11 must be 6 μm or above.Preferably, the thickness of the base layer 11 is in the range of 12 to25 μm.

The base layer 11 may be a laminated film in view of providing the baselayer 11 with a high pinhole-resistant property and an improvedinsulating ability.

Preferably, the base layer 11 includes at least one resin layerconsisting of two or more layers each having a thickness of 6 an orabove, preferably, in the range of 12 to 25 μm. The following laminatedstructures 1) to 7) are examples of the laminated base layer 11.

1) Oriented PET resin layer/Oriented nylon layer

2) Oriented nylon layer/Oriented PET layer

To improve the mechanical aptitude (stability when passed throughprocessing machines and a packaging machine) and surface protectingability (heat resistance and electrolyte resistance) of the packagingsheet and to reduce friction between a die and the base layer 11 whenforming the embossed package body, it is preferable that the base layer11 consists of plural layers and the surface of the base layer 11 iscoated with a coating of a fluorocarbon resin, an acrylic resin or asilicone resin. The base layer 11 may be any one of the followinglaminated films.

3) Fluorocarbon resin layer/Oriented PET resin layer (the fluorocarbonresin layer may be a fluorocarbon resin film or a film formed byspreading a liquid fluorocarbon resin in a film and drying the same.)

4) Silicone resin layer/Oriented PET resin layer (the silicone resinlayer may be a silicone resin film or a film formed by spreading aliquid silicone resin in a film and drying the same.)

5) Fluorocarbon resin layer/Oriented PET resin layer/Oriented nylonlayer

6) Silicone resin layer/Oriented PET resin layer/Oriented nylon layer

7) Acrylic resin layer/Oriented nylon layer (the acrylic resin layer maybe an acrylic resin film or a film formed by spreading an acrylic resinand drying the same.)

The barrier layer 12 prevents the penetration of moisture into thepolymer battery. To avoid the adverse effect of pinholes that may beformed in the barrier layer 12, to stabilize the workability (ease offabricating pouches or embossing) and to provide the barrier layer 12with pinhole resistance, the barrier layer 12 has a thickness of 15 μmor above and is formed from a foil of a metal, such as aluminum ornickel, or a film coated with an inorganic compound, such as silicondioxide or alumina, by evaporation. Preferably, the barrier layer 12 isan aluminum foil of a thickness in the range of 20 to 80.

The inventors of the present invention made studies to reduce pinholesand to prevent the cracking of an embossed battery package and foundthat an aluminum having an iron content in the range of 0.3 to 9.0% byweight, preferably, in the range of 0.7 to 2.0% by weight is moresatisfactory in ductility than aluminum not containing any iron, and analuminum foil of such aluminum is less subject to the formation ofpinholes when a laminated sheet including the aluminum foil of suchaluminum is folded and is more capable of facilitating forming walls ofan embossed battery package than an aluminum foil of aluminum notcontaining any iron. Aluminum having an iron content less than 0.3% byweight is unable to form a satisfactorily pinhole-resistant foil anddoes not have improved formability. Aluminum having an iron contentexceeding 9.0% by weight is unsatisfactory in flexibility and affectsadversely to the workability of the laminated sheet in forming a pouch.

The flexibility, stiffness and hardness of an aluminum foil formed bycold rolling are dependent on annealing conditions. The presentinvention prefers rather Soft, slightly or completely annealed aluminumfoils to those treated by a hardening process and not annealed.

Annealing conditions that affect the flexibility, stiffness and hardnessof aluminum, foils may be properly determined according to the requiredworkability (ease of forming pouches or embossed packages) of thepackaging laminated sheet. For example, to prevent the formation ofcreases or pinholes in making a package by an embossing process, a softaluminum foil properly annealed according to the degree of embossing maybe used.

The inventors of the present invention found through studies that asatisfactory packaging laminated sheet can be formed by using analuminum foil having opposite surfaces coated with chemical conversioncoatings formed by chemical conversion treatment as the barrier layer12. The chemical conversion treatment forms acid-resistant films of aphosphate, a chromate, a fluoride or a triazine thiol compound. Thus theseparation of the aluminum foil 12 and the base layer 11 during anembossing process can be prevented, the dissolution and corrosion of thesurfaces of the aluminum foil 12, particularly, aluminum oxide filmscoating the aluminum foil, by hydrogen fluoride produced by theinteraction of the electrolyte of the polymer battery module andmoisture can be effectively prevented, the adhesive property(wettability) of the surface of the aluminum foil is improved, theseparation of the base layer and the aluminum foil can be prevented andthe separation of the aluminum foil and the innermost layer due to theeffect of hydrogen fluoride produced by the interaction between theelectrolyte and moisture can be effectively prevented by the chemicalconversion treatment of the aluminum foil.

It was found through experimental chemical conversion treatment usingvarious substances that chemical conversion treatment method using amixture of a phenolic resin, trivalent chromium phosphate and phosphoricacid has satisfactory effect.

When the packaging laminated sheet is intended for use for formingpouches, only one surface on the side of the innermost layer of thealuminum foil may be processed by the chemical conversion treatment.

When both the surfaces of the aluminum foil are coated with the chemicalconversion coatings, the separation of the aluminum foil and the baselayer can be prevented when processing the packaging laminated sheet toform an embossed package. The packaging laminated sheet including thealuminum foil having both the surfaces coated with the chemicalconversion coatings may be used for forming pouches.

The inventors of the present invention made studies to develop alaminating method capable of laminating layers with stable adhesivestrength and have found that the packaging laminated sheet 10 havingcomponent layers bonded together with desired adhesive strength can beformed by bonding the base layer 11 to the chemical conversion coating15 a formed on one of the surfaces processed by chemical conversiontreatment of the barrier layer 12 by a dry lamination method and formingthe adhesive resin layer 13 of a PPa resin and the heat-sealable resinlayer 14 of an ERRPP resin by a coextrusion lamination method on theother surface of the barrier layer 12 to form a laminated structure, andheating the laminated structure at a temperature not lower than thesoftening point of the PPa resin forming the adhesive resin layer 13.

The packaging laminated sheet 10 may be heated by any one of a contactheating method using a hot roller, a hot air heating method using hotair and an infrared heating method using near or far infrared rays,provided that the adhesive resin can be heated at a temperature notlower than the softening point thereof.

The ethylene content of the ERRPP resin forming the heat-sealable resinlayer 14 is in the range of 5% to 10% by mol, preferably, in the rangeof 6% to 8% by mol.

The inventors of the present invention found that the whitening andcracking of the packaging laminated sheet when forming pouches andembossed packages can be prevented by forming the heat-sealable resinlayer 14 of an ERRPP resin.

The ERRPP resin for forming the heat-sealable resin layer 14 is flexibleas compared with an ordinary RPP resin and hence the same is inferior insliding property to the ordinary RPP resin. Therefore the heat-sealableresin layer 14 may contain an antiblocking agent (AB agent). The ABagent content of the heat-sealable resin layer 14 is in the range ofabout 0.1% to about 2.0% buy weight.

When the heat-sealable resin layer 14 consists of the layers 14 a and 14b, the inner one of the layers 14 a and 14 b may contain the AB agent.The AB agent contained in the heat-sealable resin layer 14 reduces thefriction coefficient of the surface of the heat-sealable resin layer 14,improves the sliding property of the heat-sealable resin layer 14 andimproves the workability of the polymer battery module packaging sheetwhen forming pouches or embossed packages.

Possible AB agents are inorganic lubricant powders having a meanparticle size of 15 μm or below, such as silica powder and zeolitepowder, and organic lubricant beads, such as acrylic resin beads andpolyester resin beads.

Possible PPa resins for forming the adhesive resin layer 13 are: (1)homopolymers having a melting point of 150° C. or above, (2)ethylene-propylene copolymers (random copolymers) having a Vicatsoftening point of 105° C. or above and a melting point of 130° C. orabove and (3) polymers or blend of polymers produced by acid-modifiedpolymerization using an unsaturated carboxylic acid.

The PPa resin may contain 5% or above of a low-crystallineethylene-butene copolymer having a density of 900 kg/m³ or below, alow-crystalline propylene-butene copolymer, an amorphousethylene-propylene copolymer, an amorphous pro-pylene-ethylene copolymeror an ethylene-butene-propylene terpolymer to give the PPa resin filmflexibility, to improve bendability and to prevent cracking during aforming process.

Preferably, the heat-sealable resin layer 14 of the packaging laminatedsheet of the present invention is formed of an ERRPP resin. Films of anERRPP resin can be easily bonded together by heat-sealing, meetprotective properties including moistureproof property and heatresistance required of the heat-sealable resin layer of a polymerbattery module packaging sheet, and have desirable properties suitablefor lamination and embossing.

Desirably, the heat-sealable resin layer 14 has a thickness in the rangeof 30 to 100 μm and is formed of an ERRPP resin having a melting pointof 120° C. or above.

The heat-sealable resin layer 14 may be a single film of the ERRPP resinor a multilayer film including at least one layer of the ERRPP resin.

The followings are concrete examples of the construction of theheat-sealable resin layer, in which right-hand end films are thoseforming the innermost layer facing a polymer battery module.

(1) ERRPP resin film containing AB agent(2) ERRPP resin film/ERRPP resin film containing AB agent(3) ERRPP resin film/PP resin film(4) ERRPP resin film/PP resin film/ERRPP resin film containing AB agent(5) PP resin film/ERRPP resin film containing AB agent(6) ERRPP resin film/LLDPE resin film/ERRPP resin film containing ABagent(7) ERRPP resin film/HomoPP resin film

In (1) to (7), ERRPP denotes an ethylene-rich random polypropyleneresin, PP denotes a random polypropylene having an ethylene content inthe range of 3% to 4% by mol, HomoPP denotes a homopolypropylene resin,LLDPE denotes a linear low-density polyethylene resin, “/” indicatescoextrusion.

The heat-sealable layer consisting of the ERRPP resin film and thehomoPP resin film (the construction (7)) whitens sometimes when the sameis subjected to deep drawing. However, the packaging laminated sheetprovided with such a heat-sealable layer has a satisfactoryemboss-formability because the homoPP resin film has a high slipproperty.

Desirably, the base layer 11 of the packaging laminated sheet 10, i.e.,the polymer battery module packaging sheet, of the present invention isbonded to the surface of the barrier layer 12 coated with the chemicalconversion coating 15 a by a dry lamination method.

Possible adhesives for forming the bonding layer 16 used for bonding thebase layer 11 to the chemical conversion coating 15 a of the barrierlayer 12 by dray lamination are polyester adhesives, polyethyleneadhesives, polyether adhesives, cyanoacrylate adhesives, urethaneadhesives, inorganic titanium compounds, polyether-urethane adhesives,epoxy adhesives, polyester-urethane adhesives, imide adhesives,isocyanate adhesives, polyolefin adhesives and silicone adhesives.

The packaging laminated sheet, i.e., the polymer battery modulepackaging sheet, of the present invention may include, in addition tothe base layer 11, the barrier layer 12, the adhesive resin layer 13 andthe heat-sealable resin layer 14, an intermediate layer sandwichedbetween the barrier layer 12 and the heat-sealable layer 14 to enhancethe strength of the packaging laminated sheet and to improve andstabilize the barrier property of the packaging laminated sheet.

The component layers of the packaging laminated sheet may be processedby a surface activating treatment, such as a corona discharge treatment,a blasting treatment, an oxidation treatment or ozone treatment, toimprove and stabilize film forming property, lamination property,formability (ease of forming pouches or embossed packages).

Examples Examples of the packaging laminated sheet in the ninthembodiment will be described hereinafter. The chemical conversionprocess applies an aqueous solution of a phenolic resin, trivalentchromium fluoride compound and phosphoric acid in a film to the surfaceof the barrier layer 12 by a roll coating method and baked the film at180° C. or above. The weight per unit area of the film is 10 mg/m² (dryweight).

Examples of the polymer battery module packaging sheet will beconcretely described.

Packaging laminated sheets in examples were subjected to single-sideembossing to form embossed packages each having a hollow part of 30mm×50 mm×3.5 mm. The formability of the packaging laminated sheets wasevaluated.

Examples used a PPa resin produced by acid-modified polymerization usingan unsaturated carboxylic acid and containing a RPP resin having asoftening point of 105° C. and a melting point of 146° C. as a baseresin.

ERRPP resins having an ethylene content of 7% by mol and a melting pointof 132° C. were used. RPP resins having an ethylene content of 3% by moland a melting point of 140° C. were used.

Example 9-1 Pouch

Both the surfaces of a 20 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick Film of a PPa resin as an adhesive resinfilm and a 30 μm thick film of an ERRPP resin was bonded to the othersurface of the aluminum foil by a coextrusion lamination method to forma laminated sheet. The laminated sheet was heated at a temperature notlower than the softening point of the PPa resin to obtain samplepackaging laminated sheets in Example 9-1.

Silica powder having a mean particle size of 10 μm was added to theERRPP resin film in a silica content of 0.1% by weight.

Example 9-2 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick Film of a PPa resin as an adhesive resinfilm and a 30 μm thick film of an ERRPP resin was bonded to the othersurface of the aluminum foil by a coextrusion lamination method to forma laminated sheet. The laminated sheet was heated at a temperature notlower than the softening point of the PPa resin to obtain samplepackaging laminated sheets in Example 9-2.

Silica powder having a mean particle size of 10 μm was added to theERRPP resin film in a silica content of 0.2% by weight.

Example 9-3 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Theother surface of the aluminum foil was heated at a temperature not lowerthan the softening point of a PPa resin for forming the adhesive resinfilm, and a laminated film of a 20 μm thick Film of a PPa resin as anadhesive resin film and a 30 μm thick film of an ERRPP resin was bondedto the heated surface of the aluminum foil by a coextrusion laminationmethod to obtain sample packaging laminated sheets in Example 9-3.

Silica powder having a mean particle size of 10 μm was added to theERRPP resin film in a silica content of 0.2% by weight.

Example 9-4 Embossed Package

Both the surfaces of each of 40 μm thick aluminum foils were subjectedto chemical conversion treatment. A 25 μm thick nylon film was laminatedto one of the surfaces of each of the aluminum foils by a dry laminationmethod. Laminated films each of a 20 μm thick film (adhesive resinlayer) of a PPa resin and a 30 μm thick film of an ERRPP resincontaining one of the following AB agents were formed on the othersurfaces of the aluminum foils, respectively, by a coextrusionlamination method to form laminated sheets. The laminated sheets wereheated at a temperature not lower than the softening point of the PParesin to obtain sample packaging laminated sheets in Examples 9-4-1 to9-4-4.

AB Agents

Example 9-4-1: 0.5% by weight zeolite powder having a mean particle sizeof 8 μm

Example 9-4-2: 1.2% by weight zeolite powder having a mean particle sizeof 8 μm

Example 9-4-3: 0.8% by weight acrylic resin powder having a meanparticle size of 10 μm

Example 9-4-4: 1.5% by weight acrylic resin powder having a meanparticle size of 10 μm

Example 9-5 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick Film of a PPa resin as an adhesive resinfilm and a 30 μm thick film of an ERRPP resin was bonded to the othersurface of the aluminum foil by a coextrusion lamination method to forma laminated sheet. The laminated sheet was heated at a temperature notlower than the softening point of the PPa resin to obtain samplepackaging laminated sheets in Example 9-5.

Silica powder having a mean particle size of 10 μm was added to a 5 μmthick ERRPP resin layer serving as the innermost layer of the ERRPPresin film in a silica content of 1.0% by weight.

Comparative Example 9-1 Pouch

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick Film of a PPa resin as an adhesive resinfilm and a 30 μm thick film of a PP resin having an ethylene content of3% by weight was bonded to the other surface of the aluminum foil by acoextrusion lamination method to form a laminated sheet. The laminatedsheet was heated at a temperature not lower than the softening point ofthe PPa resin to obtain sample packaging laminated sheets in Comparativeexample 9-1.

Comparative Example 9-2 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick Film of a PPa resin as an adhesive resinfilm and a 30 μm thick film of a RPP resin having an ethylene content of3% by weight was bonded to the other surface of the aluminum foil by acoextrusion lamination method to form a laminated sheet. The laminatedsheet was heated at a temperature not lower than the softening point ofthe PPa resin to obtain sample packaging laminated sheets in Comparativeexample 9-2.

Comparative Example 9-3 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick Film of a PPa resin as an adhesive resinfilm and a 30 μm thick film of an ERRPP resin was bonded to the othersurface of the aluminum foil by a coextrusion lamination method toobtain sample packaging laminated sheets in Example 9-3.

The ERRPP resin film contained silica powder having a mean particle sizeof 10 μm in 0.2% by weight.

Comparative Example 9-4 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry-lamination method. Alaminated film of a 20 μm thick Film of a PPa resin as an adhesive resinfilm and a 30 μm thick film of an ERRPP resin containing an AB agent wasbonded to the other surface of the aluminum foil by a coextrusionlamination method to form a laminated sheet. The laminated sheet washeated at a temperature not lower than the softening point of the PParesin to obtain sample packaging laminated sheets in Example 9-4.

Pouch Formation, Embossing and Packaging

The sample packaging laminated sheets in Example 9-1 and Comparativeexample 9-1 were subjected to a pouch forming process to form pouches.The sample packaging laminated sheets in Examples 9-3 to 9-5 andComparative examples 9-2 to 9-4 were subjected to single-side embossingto form embossed packages each having a hollow part of 55 mm×30 mm×3.5mm. Polymer battery modules were packaged in the pouches and theembossed packages to form polymer batteries. The polymer batteries wereevaluated by the following methods. The width of the sealed parts of thepouches and the embossed packages formed from the packaging laminatedsheets in examples and comparative examples was 5 mm.

Evaluating Methods

1) Delamination, Whitening and Cracking during Forming

Samples were inspected for the separation of the base layer and thealuminum foil, whitening and cracking immediately after forming.

2) Chemical Resistance Test

A carbonate solvent containing a lithium salt were sealed in samplepouches and sample embossed packages formed from the packaging laminatedsheets in examples and comparative examples and the sample pouches andthe sample embossed packages were inspected for the separation of thealuminum foil and the resin layer after keeping the sample pouches andthe sample embossed packages in an atmosphere of 60° C. and 90% RH in athermostat for seven days.

Results

Sample packaging laminated sheets in Examples 9-1 to 9-5 were notwhitened and not cracked during pouch formation and embossing. Crackswere formed in the inner surfaces of the bent parts of the fifteensample pouches out of 100 sample pouches formed from the packaginglaminated sheets in Comparative example 9-1. Bends in the fifty sampleembossed packages faulted from the packaging laminated sheets inComparative example 9-2 whitened slightly.

The sample embossed packages formed from the packaging laminated sheetsin Example 9-3 had no problem at all relating to whitening, cracking andchemical resistance. All the sample packaging laminated sheets inComparative example 9-3 were delaminated.

The sample packaging laminated sheets in Examples 9-4-1 to 9-4-4, whichdiffer from each other in the type and content of the AB agent, werestable in the embossing process. All the 100 sample packaging laminatedsheets in Comparative example 9-4 were creased during the embossingprocess, and pinholes were formed in the fifteen sample packaginglaminated sheets of the same.

The sample embossed packages formed from the packaging laminated sheetsin Example 9-5 were not whitened and not cracked and had no problemrelating to chemical resistance.

The packaging laminated sheets, i.e., the polymer battery modulepackaging sheets, of the present invention each provided with theheat-sealable layer of the ERRPP resin neither whiten nor crack whenbent to form a pouch and when embossed to form an embossed package. Thepouches and embossed packages formed from the packaging laminated sheetsof the present invention exhibited remarkably stable sealingperformance. The separation of the aluminum foil and the base layerduring the heat-sealing process and the embossing process could beprevented by the chemical conversion treatment of both the surfaces ofthe aluminum foil. The chemical conversion coatings formed on both thesurfaces of the aluminum foil prevented the corrosion of the surfaces ofthe aluminum foil by hydrogen fluoride produced by the interaction ofthe electrolyte of the polymer battery module and moisture and theseparation of the aluminum foil and the layer on the side of the polymerbattery module due to the corrosion of the surfaces of the aluminumfoil.

Since the ERRPP resin film serving as the heat-sealable resin layer,i.e., the innermost layer, can be bonded to the aluminum foil by the PParesin, i.e., the adhesive resin, by a coextrusion lamination method, thepackaging laminated sheet of the present invention can be manufacturedat a high productivity. The heat-sealable resin layer and the aluminumfoil can be bonded together by a sufficiently high adhesive strength bysubjecting the laminated sheet to postheating or by heating the surfaceof the aluminum foil when applying the PPa resin to the aluminum foil bya coextrusion lamination method.

Tenth Embodiment

A packaging laminated sheet, i.e., a polymer battery module packagingsheet, in a tenth embodiment according to the present invention has amoistureproof property, and is resistant to the detrimental effects ofthe polymer battery module and capable of being manufactured at a highproductivity. When forming the packaging laminated sheet, the oppositesurfaces of a barrier layer are subjected to chemical conversiontreatment, an innermost layer is laminated to the barrier layer by acoextrusion lamination method to form a laminated sheet and thelaminated sheet is subjected to a heating process to enhance theadhesive strength between the component layers.

The inventors of the present invention made earnest studies to developsuch a packaging laminated sheet, and found that the foregoing problemscan be solved by subjecting both the surfaces of an aluminum foil tochemical conversion treatment, forming an adhesive resin layer of a PParesin, such as an unsaturated carboxylic acid graft random acid-modifiedpolypropylene resin, on one of the surfaces of the aluminum foil andforming an innermost layer of an ERRPP resin, and by a packaginglaminated sheet manufacturing method including the steps of subjectingboth the surfaces of an aluminum foil to chemical conversion treatment,extruding a PPa resin as an adhesive resin onto the inner surface of thealuminum foil, laminating an ERRPP resin film to the aluminum foil by asandwich lamination method to form a laminated sheet and subjecting thelaminated sheet to postheating.

Postheating enhances the adhesive strength between the barrier layer andthe adhesive resin layer and between the adhesive resin layer and theinnermost layer.

The adhesive strength may be enhanced by a method that heats the surfaceto which the adhesive resin layer is to be bonded of the aluminum foilat a temperature not lower than the softening point of the PPa resinwhen extruding the PPa resin onto the surface of the aluminum foil forsandwich lamination.

As shown in FIG. 11( a), a packaging laminated sheet 10, i.e., a polymerbattery module packaging sheet, in the tenth embodiment has, asessential components, a base layer 11, a bonding layer 16, a chemicalconversion coating 15 a, an aluminum foil (aluminum layer) 12, achemical conversion coating 15 b, an adhesive resin layer 13 and aheat-sealable resin layer (innermost layer) 14. The adhesive resin layer13 is formed of a PPa resin and the heat-sealable resin layer 14 isformed of an ERRPP resin. The heat-sealable resin layer 14 may consistof innermost resin films 14 a and 14 b as shown in FIG. 11( b). At leasteither the innermost resin film 14 a or 14 b may be formed of an ERRPPresin. The adhesive resin layer 13 and the heat-sealable resin layer 14constitute an innermost layer.

In the sandwich lamination process the surface of the aluminum foil 12facing the heat-sealable layer 14 is heated at a temperature not lowerthan the softening point of the PPa resin or the packaging laminatedsheet 10 is subjected to postheating to heat the packaging laminatedsheet 10 at a temperature not lower than the softening point of the PParesin. As shown in FIG. 11( a) or 11(b), chemical conversion coatings 15a and 1 b are formed on both the surfaces, respectively, of the aluminumfoil 12, i.e., the barrier layer, the adhesive resin layer 13 is formedon the inner surface of the aluminum foil 12 by extrusion and theheat-sealable resin layer 14 of the ERRPP resin is bonded to the innersurface of the aluminum foil 12 by the adhesive resin layer 13 by asandwich lamination method (FIG. 9). The packaging laminate sheet 10thus formed is subjected to postheating or the inner surface of thealuminum foil 12 is heated at a temperature not lower than the softeningpoint of the PPa resin forming the adhesive resin layer 13.

The packaging laminated sheet 10, i.e., the polymer battery modulepackaging sheet, in the tenth embodiment has, as essential components,the base layer 11, the chemical conversion coating 15 a, the barrierlayer 12, i.e., the aluminum foil, the chemical conversion coating 15 b,the adhesive resin layer 13 and the heat-sealable resin layer 14. Theheat-sealable resin layer 14 is laminated to the aluminum foil 12 by asandwich lamination method. The heat-sealable layer 14 is a multilayerfilm including at least one of the layers 14 a and 14 b of an ERRPPresin.

Materials of the component layers of the laminated sheet 10 and methodsof laminating the component layers will be described.

The base layer 11 of the packaging laminated sheet 10 is a film of anoriented polyester resin or an oriented nylon resin. Possible polyesterresins are PET resins, PBT resins, PEN resins, PBN resins,interpolyester resins, PC resins and the like. Possible nylons, i.e.,polyamide resins, are nylon 6, nylon 66, copolymers of nylon 6 and nylon66, nylon 610, polymethaxylilene adipamide (MXD6) and the like.

When the polymer battery is used on a device (hardware), the base layer11 touches the device. Therefore, it is desirable to form the base layer11 of an intrinsically insulating resin. Since a film forming the baselayer 11 has pinholes and pinholes will be formed in the film duringprocessing, the thickness of the base layer 11 must be 6 μm or above.Preferably, the thickness of the base layer 11 is in the range of 12 to25 μm.

The base layer 11 may be a laminated film in view of providing the baselayer 11 with a high pinhole-resistant property and an improvedinsulating ability.

Preferably, the base layer 11 includes at least one resin layerconsisting of two or more layers each having a thickness of 6 μm orabove, preferably, in the range of 12 to 25 μm. The following laminatedstructures 1) to 7) are examples of the laminated base layer 11.

1) Oriented PET resin layer/Oriented nylon layer

2) Oriented nylon layer/Oriented PET layer

To improve the mechanical aptitude (stability when passed throughprocessing machines and a packaging machine) and surface protectingability (heat resistance and electrolyte resistance) of the packagingsheet and to reduce friction between a die and the base layer 11 whenforming the embossed package body, it is preferable that the base layer11 consists of plural layers and the surface of the base layer 11 iscoated with a coating of a fluorocarbon resin, an acrylic resin or asilicone resin. The base layer 11 may be any one of the followinglaminated films.

3) Fluorocarbon resin layer/Oriented PET resin layer (the fluorocarbonresin layer may be a fluorocarbon resin film or a film formed byspreading a liquid fluorocarbon resin in a film and drying the same.)

4) Silicone resin layer/Oriented PET resin layer (the silicone resinlayer may be a silicone resin film or a film formed by spreading aliquid silicone resin in a film and drying the same.)

5) Fluorocarbon resin layer/Oriented PET resin layer/Oriented nylonlayer

6) Silicone resin layer/Oriented PET resin layer/Oriented nylon layer

7) Acrylic resin layer/Oriented nylon layer (the acrylic resin layer maybe an acrylic resin film or a film formed by spreading an acrylic resinand drying the same.)

The barrier layer 12 prevents the penetration of moisture into thepolymer battery. To avoid the adverse effect of pinholes that may beformed in the barrier layer 12, to stabilize the workability (ease offabricating pouches or embossing) and to provide the barrier layer 12with pinhole resistance, the barrier layer 12 has a thickness of 15 μmor above and is formed from a foil of a metal, such as aluminum ornickel, or a film coated with an inorganic compound, such as silicondioxide or alumina, by evaporation. Preferably, the barrier layer 12 isan aluminum foil of a thickness in the range of 20 to 80 μm.

The inventors of the present invention made studies to reduce pinholesand to prevent the cracking of an embossed battery package and foundthat an aluminum having an iron content in the range of 0.3 to 9.0% byweight, preferably, in the range of 0.7 to 2.0% by weight is moresatisfactory in ductility than aluminum not containing any iron, and analuminum foil of such aluminum is less subject to the formation ofpinholes when a laminated sheet including the aluminum foil of suchaluminum is folded and is more capable of facilitating forming walls ofan embossed battery package than an aluminum foil of aluminum notcontaining any iron. Aluminum having an iron content less than 0.3% byweight is unable to form a satisfactorily pinhole-resistant foil anddoes not have improved formability. Aluminum having an iron contentexceeding 9.0% by weight is unsatisfactory in flexibility and affectsadversely to the workability of the laminated sheet in forming a pouch.

The flexibility, stiffness and hardness of an aluminum foil formed bycold rolling are dependent on annealing conditions. The presentinvention prefers rather soft, slightly or completely annealed aluminumfoils to those treated by a hardening process and not annealed.

Annealing conditions that affect the flexibility, stiffness and hardnessof aluminum foils may be properly determined according to the requiredworkability (ease of forming pouches or embossed packages) of thepackaging laminated sheet. For example, to prevent the formation ofcreases or pinholes in making a package by an embossing process, a softaluminum foil properly annealed according to the degree of embossing maybe used.

The inventors of the present invention found through studies that asatisfactory packaging laminated sheet can be formed by using analuminum foil having opposite surfaces coated with chemical conversioncoatings formed by chemical conversion treatment as the barrier layer12. The chemical conversion treatment forms acid-resistant films of aphosphate, a chromate, a fluoride or a triazine thiol compound. Thus theseparation of the aluminum foil 12 and the base layer 11 during anembossing process can be prevented, the dissolution and corrosion of thesurfaces of the aluminum foil 12, particularly, aluminum oxide filmscoating the aluminum foil, by hydrogen fluoride produced by theinteraction of the electrolyte of the polymer battery module andmoisture can be effectively prevented, the adhesive property(wettability) of the surface of the aluminum foil is improved, theseparation of the base layer and the aluminum foil can be prevented andthe separation of the aluminum foil and the innermost layer due to theeffect of hydrogen fluoride produced by the interaction between theelectrolyte and moisture can be effectively prevented by the chemicalconversion treatment of the aluminum foil.

It was found through experimental chemical conversion treatment usingvarious substances that chemical conversion treatment method using amixture of a phenolic resin, trivalent chromium phosphate and phosphoricacid has satisfactory effect.

When the packaging laminated sheet is intended for use for formingpouches, only one surface on the side of the innermost layer 14 of thealuminum foil 12 may be processed by the chemical conversion treatment.

When both the surfaces of the aluminum foil are coated with the chemicalconversion coatings, the separation of the aluminum foil 12 and the baselayer 11 can be prevented when processing the packaging laminated sheetto form an embossed package. The packaging laminated sheet including thealuminum foil 12 having both the surfaces coated with the chemicalconversion coatings may be used for forming pouches.

The inventors of the present invention made studies to develop alaminating method capable of laminating layers with stable adhesivestrength and have found that the packaging laminated sheet 10 havingcomponent layers bonded together with desired adhesive strength can beformed by bonding the base layer 11 to the chemical conversion coating15 a formed on one of the surfaces processed by chemical conversiontreatment of the barrier layer 12 by a dry lamination method forming theadhesive resin layer 13 of a PPa resin and the heat-sealable resin layer14 of an ERRPP resin by a sandwich lamination method on the othersurface of the barrier layer 12 coated with the chemical conversioncoating 15 b to form a laminated structure, and heating the laminatedstructure at a temperature not lower than the softening point of the PParesin forming the adhesive resin layer 13.

The packaging laminated sheet 10 may be heated by any one of a contactheating method using a hot roller, a hot air heating method using hotair and an infrared heating method using near or far infrared rays,provided that the adhesive resin can be heated at a temperature notlower than the softening point thereof.

The inner surface of the aluminum foil 12 on the side of theheat-sealable resin layer 14 may be heated at a temperature not lowerthan the softening point of the PPa resin during sandwich lamination toprovided a laminated structure having stable adhesive strength.

The ethylene content of the ERRPP resin forming the heat-sealable resinlayer 14 is in the range of 5% to 10% by mol, preferably, in the rangeof 6% to 8% by mol.

The inventors of the present invention found that the whitening andcracking of the packaging laminated sheet when forming pouches andembossed packages can be prevented by forming the heat-sealable resinlayer 14 of an ERRPP resin.

The ERRPP resin for forming the heat-sealable resin layer 14 is flexibleas compared with an ordinary RPP resin and hence the same is inferior insliding property to the ordinary RPP resin. Therefore the heat-sealableresin layer 14 may contain an antiblocking agent (AB agent). The ABagent content of the heat-sealable resin layer 14 is in the range ofabout 0.1% to about 2.0% buy weight.

When the heat-sealable resin layer 14 consists of the layers 14 a and 14b, the inner one of the layers 14 a and 14 b may contain the AB agent.The AB agent contained in the heat-sealable resin layer 14 reduces thefriction coefficient of the surface of the heat-sealable resin layer 14,improves the sliding property of the heat-sealable resin layer 14 andimproves the workability of the polymer battery module packaging sheetwhen forming pouches or embossed packages.

Possible AB agents are inorganic lubricant powders having a meanparticle size of 15 μm or below, such as silica powder and zeolitepowder, and organic lubricant beads, such as acrylic resin beads andpolyester resin beads.

Possible PPa resins for forming the adhesive resin layer 13 are: (1)homopolymers having a Vicat softening point of 115° C. or above and amelting point of 150° C. or above, (2) ethylene-propylene copolymers(random copolymers) having a Vicat softening point of 105° C. or aboveand a melting point of 130° C. or above and (3) polymers or blend ofpolymers produced by acid-modified polymerization using an unsaturatedcarboxylic acid.

The PPa resin may contain 5% or above of a low-crystallineethylene-butene copolymer having a density of 900 kg/m³ or below, alow-crystalline propylene-butene copolymer, an amorphousethylene-propylene copolymer, an amorphous pro-pylene-ethylene copolymeror an ethylene-butene-propylene terpolymer to give the PPa resin filmflexibility, to improve bendability and to prevent cracking during aforming process.

Preferably, the heat-sealable resin layer 14 of the packaging laminatedsheet of the present invention is formed of an ERRPP resin. Films of anERRPP resin can be easily bonded together by heat-sealing, meetprotective properties including moistureproof property and heatresistance required of the heat-sealable resin layer of a polymerbattery module packaging sheet, and have desirable properties suitablefor lamination and embossing.

Desirably, the heat-sealable resin layer 14 has a thickness in the rangeof 30 to 100 μm and is formed of an ERRPP resin having a melting pointof 120° C. or above.

The heat-sealable resin layer 14 may be a single film of the ERRPP resinor a multilayer film including at least one layer of the ERRPP resin.

The followings are concrete examples of the construction of theheat-sealable resin layer, in which right-hand end films are thoseforming the innermost layer facing a polymer battery module.

(1) ERRPP resin film containing AB agent(2) ERRPP resin film/ERRPP resin film containing AB agent(3) ERRPP resin film/PP resin film(4) ERRPP resin film/PP resin film/ERRPP resin film containing AB agent(5) PP resin film/ERRPP resin film containing AB agent(6) ERRPP resin film/LLDPE resin film/ERRPP resin film containing ABagent(7) ERRPP resin film/HomoPP resin filmIn (1) to (7) ERRPP denotes an ethylene-rich random polypropylene resin,PP denotes a random polypropylene having an ethylene content in therange of 3% to 4% by mol, HomoPP denotes a homopolypropylene resin,LLDPE denotes a linear low-density polyethylene resin, “/” indicatescoextrusion.

The heat-sealable layer consisting of the ERRPP resin film and thehomoPP resin film (the construction (7)) whitens sometimes when the sameis subjected to pouch formation. However, the packaging laminated sheetprovided with such a heat-sealable layer has a satisfactoryemboss-formability because the homoPP resin film has a high slipproperty.

The packaging laminated sheet 10, i.e., the polymer battery modulepackaging sheet, of the present invention may include, in addition tothe base layer 11, the barrier layer 12, the adhesive resin layer 13 andthe heat-sealable resin layer 14, an intermediate layer sandwichedbetween the barrier layer 12 and the heat-sealable layer 14 to enhancethe strength of the packaging laminated sheet and to improve andstabilize the barrier property of the packaging laminated sheet.

The component layers of the packaging laminated sheet 10 may beprocessed by a surface activating treatment, such as a corona dischargetreatment, a blasting treatment, an oxidation treatment or ozonetreatment, to improve and stabilize film forming property, laminationproperty, formability (ease of forming pouches or embossed packages).

Desirably, the base layer 11 of the packaging laminated sheet 10, i.e.,the polymer battery module packaging sheet, is bonded to the surface ofthe barrier layer 12 coated with the chemical conversion coating 15 a bya dry lamination method.

Possible adhesives for fainting the bonding layer 16 used for bondingthe base layer 11 to the chemical conversion coating 15 a of the barrierlayer 12 by dray lamination are polyester adhesives, polyethyleneadhesives, polyethylene imine adhesives, polyether adhesives,cyanoacrylate adhesives, urethane adhesives, inorganic titaniumcompounds, polyether-urethane adhesives, epoxy adhesives,polyester-urethane adhesives, epoxy adhesives, polyester-urethaneadhesives, imide adhesives, isocyanate adhesives, polyolefin adhesivesand silicone adhesives.

Examples

Examples of the packaging laminated sheet in the tenth embodiment willbe described hereinafter. The chemical conversion process applies anaqueous solution of a phenolic resin, trivalent chromium fluoridecompound and phosphoric acid in a film to the surface of the barrierlayer 12 by a roll coating method and baked the film at 180° C. orabove. The weight per unit area of the film is 10 mg/m² (dry weight).

Examples of the polymer battery module packaging sheet will beconcretely described.

Packaging laminated sheets in examples were subjected to single-sideembossing to form embossed packages each having a hollow part of 30mm×50 mm×3.5 mm. The formability of the packaging laminated sheets wasevaluated.

Examples used a PPa resin produced by acid-modified polymerization usingan unsaturated carboxylic acid and containing a RPP resin having asoftening point of 105° C. and a melting point of 146° C. as a baseresin.

ERRPP resins having an ethylene content of 7% by mol and a melting pointof 132° C. were used. RPP resins having an ethylene content of 3% by moland a melting point of 140° C. were used.

Example 10-1 Pouch

Both the surfaces of a 20 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick Film of a PPa resin as an adhesive resinfilm and a 30 μm thick film of an ERRPP resin was bonded to the othersurface of the aluminum foil by a sandwich lamination method to form alaminated sheet. The laminated sheet was heated at a temperature notlower than the softening point of the PPa resin to obtain samplepackaging laminated sheets in Example 10-1.

Silica powder having a mean particle size of 10 μm was added to theERRPP resin film in a silica content of 0.2% by weight.

Example 10-2 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick Film of a PPa resin as an adhesive resinfilm and a 30 μm thick film of an ERRPP resin was bonded to the othersurface of the aluminum foil by a sandwich lamination method to form alaminated sheet. The laminated sheet was heated at a temperature notlower than the softening point of the PPa resin to obtain samplepackaging laminated sheets in Example 10-2.

Silica powder having a mean particle size of 10 μM was added to theERRPP resin film in a silica content of 0.2% by weight.

Example 10-3 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Theother surface of the aluminum foil was heated at 150° C. by irradiatingthe same surface with infrared rays and blowing hot air against the samesurface while a laminated film of a 20 μm thick Film of a PPa resin asan adhesive resin film and a 30 μm thick film of an ERRPP resin wasbeing bonded to the heated surface of the aluminum foil by a sandwichlamination method to obtain sample packaging laminated sheets in Example10-3.

Silica powder having a mean particle size of 10 μm was added to theERRPP resin film in a silica content of 0.2% by weight.

Example 10-4 Embossed Package

Both the surfaces of each of 40 μm thick aluminum foils were subjectedto chemical conversion treatment. A 25 μm thick nylon film was laminatedto one of the surfaces of each of the aluminum foils by a dry laminationmethod. Laminated films each of a 20 μm thick film (adhesive resinlayer) of a PPa resin and a 30 μm thick film of an ERRPP resincontaining one of the following AB agents were formed on the othersurfaces of the aluminum foils, respectively, by a sandwich laminationmethod to form laminated sheets. The laminated sheets were heated at atemperature not lower than the softening point of the PPa resin toobtain sample packaging laminated sheets in Examples 10-4-1 to 10-4-4.

AB Agents

Example 10-4-1: 0.5% by weight zeolite powder having a mean particlesize of 8 μm

Example 10-4-2: 1.2% by weight zeolite powder having a mean particlesize of 8 μm

Example 10-4-3: 0.8% by weight acrylic resin powder having a meanparticle size of 10 μm

Example 10-4-4: 1.5% by weight acrylic resin powder having a meanparticle size of 10 μm

Example 10-5 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick Film of a PPa resin as an adhesive resinfilm and a 30 μm thick multilayer film consisting of a 5 μm thick ERRPPresin film, a 20 μm thick PP resin film and a 5 μm thick ERRPP resinfilm was bonded to the other surface of the aluminum foil by a sandwichlamination method to form a laminated sheet. The laminated sheet washeated at a temperature not lower than the softening point of the PParesin to obtain sample packaging laminated sheets in Example 10-5.

Silica powder having a mean particle size of 10 μm was added to the 5 μmthick ERRPP resin film serving as the innermost layer of the multilayerfilm in a silica content of 0.2% by weight.

Comparative Example 10-1 Pouch

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick Film of a PPa resin as an adhesive resinfilm and a 30 μm thick film of a PP resin was bonded to the othersurface of the aluminum foil by a sandwich lamination method to form alaminated sheet. The laminated sheet was heated at a temperature notlower than the softening point of the PPa resin to obtain samplepackaging laminated sheets in Comparative example 10-1.

Comparative Example 10-2 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick Film of a PPa resin as an adhesive resinfilm and a 30 μm thick film of a PP resin was bonded to the othersurface of the aluminum foil by a sandwich lamination method to form alaminated sheet. The laminated sheet was heated at a temperature notlower than the softening point of the PPa resin to obtain samplepackaging laminated sheets in Comparative example 10-2.

Comparative Example 10-3 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry lamination method. Alaminated film of a 20 μm thick Film of a PPa resin as an adhesive resinfilm and a 30 μm thick film of an ERRPP resin was bonded to the othersurface of the aluminum foil by a sandwich lamination method to obtainsample packaging laminated sheets in Example 10-3.

The ERRPP resin film contained silica powder having a mean particle sizeof 10 μm in 0.2% by weight.

Comparative Example 10-4 Embossed Package

Both the surfaces of a 40 μm thick aluminum foil were subjected tochemical conversion treatment. A 25 μm thick nylon film was laminated toone of the surfaces of the aluminum foil by a dry-lamination method. Alaminated film of a 20 μm thick Film of a PPa resin as an adhesive resinfilm and a 30 μm thick film of an ERRPP resin not containing any ABagent was bonded to the other surface of the aluminum foil by a sandwichlamination method to form a laminated sheet. The laminated sheet washeated at a temperature not lower than the softening point of the PParesin to obtain sample packaging laminated sheets in Example 10-4.

Pouch Formation, Embossing and Packaging

The sample packaging laminated sheets in Example 10-1 and Comparativeexample 10-1 were subjected to a pouch forming process to form pouches.The sample packaging laminated sheets in Examples 10-2 to 10-5 andComparative examples 10-2 to 10-4 were subjected to single-sideembossing to form embossed packages each having a hollow part of 55mm×30 mm×3.5 mm. Polymer battery modules were packaged in the 100pouches of each example and each comparative example and the 100embossed packages of each example and each comparative example to formpolymer batteries. The polymer batteries were evaluated by the followingmethods. The width of the sealed parts of the pouches and the embossedpackages formed from the packaging laminated sheets in examples andcomparative examples was 5 mm.

Evaluating Methods

1) Delamination, Whitening and Cracking during Forming

Samples were inspected for the separation of the base layer and thealuminum foil, whitening and cracking immediately after forming.

2) Chemical Resistance Test

A carbonate solvent containing a lithium salt were sealed in samplepouches and sample embossed packages formed from the packaging laminatedsheets in examples and comparative examples and the sample pouches andthe sample embossed packages were inspected for the separation of thealuminum foil and the resin layer after keeping the sample pouches andthe sample embossed packages in an atmosphere of 60° C. and 90% RH in athermostat for seven days.

Results

Sample packaging laminated sheets in Examples 10-1 to 10-5 were notwhitened and not cracked during pouch formation and embossing. Crackswere formed in the inner surfaces of the bent parts of the fifteensample pouches out of 100 sample pouches formed from the packaginglaminated sheets in Comparative example 10-1. Bends in the fifty sampleembossed packages formed from the packaging laminated sheets inComparative example 10-2 whitened.

The sample embossed packages formed from the packaging laminated sheetsin Example 10-3 had no problem at all relating to whitening, cracking.All the sample packaging laminated sheets in Comparative example 10-3were delaminated.

The sample packaging laminated sheets in Examples 9-4-1 to 9-4-4, whichdiffer from each other in the type and content of the AB agent, werestable in the embossing process. All the 100 sample packaging laminatedsheets in Comparative example 10-4 were creased during the embossingprocess, and pinholes were formed in the twenty sample packaginglaminated sheets of the same.

The sample embossed packages formed from the packaging laminated sheetsin Example 10-5 were not whitened and not cracked and had no problemrelating to chemical resistance.

The packaging laminated sheets, i.e., the polymer battery modulepackaging sheets, of the present invention each provided with theheat-sealable layer of the ERRPP resin neither whiten nor crack whenbent to form a pouch and when embossed to form an embossed package. Thepouches and embossed packages formed from the packaging laminated sheetsof the present invention exhibited remarkably stable sealingperformance. The separation of the aluminum foil and the base layerduring the heat-sealing process and the embossing process could beprevented by the chemical conversion treatment of both the surfaces ofthe aluminum foil. The chemical conversion coatings formed on both thesurfaces of the aluminum foil prevented the corrosion of the surfaces ofthe aluminum foil by hydrogen fluoride produced by the interaction ofthe electrolyte of the polymer battery module and moisture and theseparation of the aluminum foil and the layer on the side of the polymerbattery module due to the corrosion of the surfaces of the aluminumfoil.

Since the ERRPP resin film serving as the heat-sealable resin layer,i.e., the innermost layer, can be bonded to the aluminum foil by the PParesin, i.e., the adhesive resin, by a sandwich lamination method, thepackaging laminated sheet of the present invention can be manufacturedat a high productivity. The heat-sealable resin layer and the aluminumfoil can be bonded together by a sufficiently high adhesive strength bysubjecting the laminated sheet to postheating or by heating the surfaceof the aluminum foil when applying the PPa resin to the aluminum foil bya sandwich lamination method.

1. A polymer battery module packaging sheet comprising: an orientedpolyester film, an oriented nylon film, an aluminum layer, a chemicalconversion coating, an adhesive layer, and a heat-sealable resin layer,the above layers being provided in this order.
 2. The polymer batterymodule packaging sheet according to claim 1, wherein the aluminum layerhas an iron content of 0.3 to 0.9 percent by weight.
 3. The polymerbattery module packaging sheet according to claim 1, wherein thechemical conversion coating is formed from an aqueous solutioncomprising a mixture of a phenolic resin, a trivalent chromium fluoridecompound, and phosphoric acid.
 4. The polymer battery module packagingsheet according to claim 1, wherein the adhesive layer is formed of anacid-modified polyolefin resin, and the heat-sealable resin layer isformed of an ethylene-propylene copolymer resin.
 5. The polymer batterymodule packaging sheet according to claim 1, wherein the aluminum layerhas an iron content of 0.3 to 0.9 percent by weight, the chemicalconversion coating is formed from an aqueous solution comprising amixture of a phenolic resin, a trivalent chromium fluoride compound, andphosphoric acid, the adhesive layer is formed of an acid-modifiedpolyolefin resin, and the heat-sealable resin layer is formed of anethylene-propylene copolymer resin.
 6. The polymer battery modulepackaging sheet according to claim 1, wherein the adhesive layer isformed of an acid-modified polypropylene resin, the heat-sealable resinlayer is a film of a polypropylene resin, and the adhesive layer and theheat-sealable resin layer are formed by a sandwich lamination method. 7.The polymer battery module packaging sheet according to claim 1, whereinthe aluminum layer has an iron content of 0.3 to 0.9 percent by weight,the chemical conversion coating is formed from an aqueous solutioncomprising a mixture of a phenolic resin, a trivalent chromium fluoridecompound, and phosphoric acid, the adhesive layer is formed of anacid-modified polypropylene resin, the heat-sealable resin layer is afilm of a polypropylene resin, and the adhesive layer and theheat-sealable resin layer are formed by a sandwich lamination method. 8.The polymer battery module packaging sheet according to claim 1, whereinthe adhesive layer contains an acid-modified polypropylene resin, theheat-sealable resin layer contains an ethylene-butene-propyleneterpolymer, and the adhesive layer and the heat-sealable resin layer areformed by a coextrusion lamination method.
 9. The polymer battery modulepackaging sheet according to claim 1, wherein the aluminum layer has aniron content of 0.3 to 0.9 percent by weight, the chemical conversioncoating is formed from an aqueous solution comprising a mixture of aphenolic resin, a trivalent chromium fluoride compound, and phosphoricacid, the adhesive layer contains an acid-modified polypropylene resin,the heat-sealable resin layer contains an ethylene-butene-propyleneterpolymer, and the adhesive layer and the heat-sealable resin layer areformed by a coextrusion lamination method.
 10. The polymer batterymodule packaging sheet according to claim 1, wherein an additionalchemical conversion coating is interposed between the oriented nylonfilm and the aluminum layer.
 11. The polymer battery module packagingsheet according to claim 1, wherein the heat-sealable resin layer isformed of an ethylene-rich polypropylene resin.
 12. The polymer batterymodule packaging sheet according to claim 1, wherein the adhesive layeris formed of a material containing an acid-modified polypropylene resinas a principal component, the heat-sealable resin layer includes a layerformed of an ethylene-rich random polypropylene resin having an ethylenecontent in the range of 5% to 10% by mol, and the adhesive layer and theheat-sealable resin layer are formed by a sandwich lamination method.13. The polymer battery module packaging sheet according to claim 4,wherein the ethylene-propylene copolymer resin is ethylene-rich-randompolypropylene resin.
 14. The polymer battery module packaging sheetaccording to claim 1, wherein the aluminum layer covers an entiresurface of the base layer.